Fire Emblem Heroes can be quite generous with the items they distribute to players, although some of them have a catch that isn't always easy to accomplish.
- The "Use a team of sword users to clear (Book I) Chapter 7: Part 3 on Lunatic" from the February 2017 Sword Mastery quests. Not only is the map itself a pain without 2-range attacks, there is also a certain generic Lance Knight, who normally would have been roadkill for any team packing green units or magic of any kind. This was before Skill Inheritance, so players had to rely on default kits of each sword user - which for the most part just "tink"'d against the Knight, and while Hana and Caeda used Armorslayers, and so could deal damage, they were also just squishy enough to get oneshotted in retaliation. In the end, the only ones to complete this quest were those who were lucky enough to get Lucina, as she had just enough strength to damage the knight, just enough health to not die in response, while Falchion provided her something no other sword user had at that point - Renewal, thus allowing her to slooooowly deliver a Death of a Thousand Cuts over hundreds of turns.
- March 2017 Normal difficulty Monthly quest "Kill 5 enemies with armored allies". Guess which unit type was NOT available outside of gacha at the time, leaving players at the mercy of Random Number God? Even worse, since this was a Normal difficulty quest, it also gated Hard and Lunatic quests behind itself. Ultimately, IS realized the problem, and did give out a 2-star armored hero as a quest reward (Draug).
- “Clear Tenth Stratum of the Training Tower using only X type allies. All four allies must survive.” quests are multiple layers of Luck Based Missions in Luck-Based Missions. While they do reward invaluable Orbs to summon new units, their absurd difficulty prevents even players with strong benches from completing them. The Tenth Stratum's status as a randomly generated den of powerful enemies combined with being forced to deploy a full team of a particular type of unit is a hellish combination. While infantry and cavalry versions of this quest are generally doable due to their flexibility and multiple units of those types being given for free, Flier and full armor teams consist of units who are harder to acquire, have common weaknesses (Archers and Mages, Anti-Armor), and are near-exclusively melee combatants (no Dancers, no healer, no ranged attacks). While full teams can benefit from the powerful Goad/Hone buffs, these are exclusive to units of higher rarity that a player has no guarantee of drawing. Armor is further hampered by most of their common units being slow, tanky, and not particularly strong. On top of all these restrictions, a player must make FIFTEEN deathless runs of the Tenth Stratum just to clear one of these quests and deploy a full team of four, meaning if the player didn't luck into a full flier/armor team, no credit will be received even if the Tenth Stratum is cleared flawlessly. Assuming perfect play and lucky unit compositions in the Tenth Stratum, this requires a bare minimum of 135 stamina. Recent updates have somewhat alleviated this issue thanks to the ability to check maps in advance and the ability to swap out the Training Tower units, but it's still quite the slog.
- The reward structure behind the "Dark Clouds Over Awakening" Tempest Trials gave out rewards for accumulating a certain number of points; the unique rewards stopped at 50,000 and there were Orbs given out up to 100,000. A player with a min-maxed Arena team could burn through the most difficult version of the trials for 500 points (700 if they use a bonus character); which means more than 70 full runs at the hardest difficulty just for the unique rewards, or over 140 for all the rewards. At 20 stamina per attempt, the player would have to use all their stamina for most of the two week event to get all the rewards, unless they want to use their limited supply of stamina potions or Orbs to recharge. For players without a top-tier Arena team, they'd have to spend all their stamina over the entire two weeks on Hard mode to get the unique rewards, with no hope of getting any of the Orbs in the 60-100,000 point range. And as if to rub salt in the wound, two other limited time events happened at the same time (Zephiel's 2nd GHB and Legion's GHB) that also required stamina.
- While Chain Challenges can get pretty difficult on Lunatic, the one for Chapters 11 and 12 from Book I might be the hardest in the game so far. Not only are the enemy stats very inflated, it also contains 11-3 and 11-5 as described above and multiple timed missions on the second half with some of those having enemies starting on or near defense tiles. You only have 3 teams to beat the challenge and messing up even once can often force a restart, since you will need extremely specific units to clear the Chapter 11 part of the challenge and you will require very different units for the Chapter 12 part.
- A lot of the quests that appear with the Grand Hero Battles (especially the re-runs) are considered this. One infamous quest in particular is beating Fallen Takumi with only an armor team when 1) armor teams are hard to optimize without heavy Skill Inheritance (which means multiple lucky summons), and 2) Fallen Takumi's map gimmick is tailor-made to wreak havoc on armors. Thankfully, most of these don't force you to clear it on Infernal, only on Lunatic, but even then, you'll need to make sure the quest units have an appropriate build.
- Relay Defense, a brigade-based mode that takes place on Rival Domains every now and then, is nothing short of frustrating. Its intent is simple, being a defend map where the player uses five units at a time that swap out every few turns to defend against waves and waves of reinforcements. The problem however, is that it's just complete enemy spam of differing weapon types and colours, which will easily overwhelm the player's units. While the first few difficulties are at least reasonable, the harder difficulties become too overwhelming, especially on the Abyssal difficulty maps that have enemy units with stats so high that they become nearly unkillable in a single round, all while there's at least several enemies waiting to get the jump on the player too. The worst of it is that there are actually decent rewards like Feathers and Orbs, which actually gives players incentive to try it out. This mode was understandably given the nerf bat in one more future appearance, and eventually just cut from the game altogether.
- The second set of maps added to the Blessed Gardens. While the first tier of maps were focused around using one team on several maps, the later maps changed to be where you needed several teams for several maps. The difficulty of creating upwards of three teams of units using the needed elemental blessing, with the maps being all different, meant that few players ever bothered to do it unless the reward was orbs. The result was that ultimately players stopped using the mode, and the developers, seemingly aware of this, stopped updating the mode by the end of May 2019.
- "Clear a Grand Hero Battle on Abyssal" from Heroes' Path quests. Considering just how hard Abyssal difficulty is, this quest is incredibly difficult for Free-to-Play players without using a guide and specific heroes like Brave Veronica. Since it's a Rank 15 quest, not clearing it means losing out on a few rewards, namely 3 Orbs, 1 Stamina Potion, and a copy of Brave Ike, a very powerful tank unit.
- The 150000 damage to a Røkkr in a single battle of Røkkr Sieges to get the Røkkr Remnant accessories. To even have a chance to reach that score, you need to go on the Intermediate and Advanced difficulties and spend either all 8 of your stamina on Intermediate and at least 6 stamina on Advanced, but it's recommended to spend all 8 to increase the room for error. Worse still, you have a limited amount of time and Havoc Axes to deal that amount of damage, and the Røkkr has increased stats on the higher difficulties to deal more pain, take less damage, and be fast enough to be normally not doubled by Mighty Glacier and Jack of All Stats units. Dealing damage in the hundred thousands is demanding enough, but this quest takes the cake in that not only do you need the right heroes and skill sets to reach that amount of damage to a specific Røkkr, but it's a Luck-Based Mission due to the random spawn of generic enemies in the Intermediate and Advanced difficulty, such as Bow units targeting your fliers and Armor units taking Chill debuffs instead of the Røkkr, and the map choice being more obstructive to you than to your enemies. You can increase your damage if you exploit their movement and weapon weakness with effective weapons, but for Røkkr who do not have any, you're down to just dealing enough raw damage.
- Limited Hero Battles - these were introduced in the Version 4.0 update and rewards Feathers and Divine Codes, and are basically the same as previous Grand, Bound, Legendary and Mythic Battle maps. However, they restrict your teams based on the games that they're from, and some of them even restrict uses of Dance/Sing skills. Depending on how you've been collecting heroes and making teams, you could either have a game or two with a really solid team lineup, a game that has a hero or two that carry your entire team, or a game with a horrible setup, with only characters from Tokyo Mirage Sessions ♯FE being excluded due to the small amount of heroes from that game.
- The worst ones however, are the Abyssal versions of Legendary and Mythic Hero Battle maps after May 2020, where unlike the previous versions where they use the Infernal stats, they use the actual Abyssal stats, which means that you're going to have trouble without premium units. One example is the Abyssal version of Legendary Ryoma's battle, where you're stuck using the The Blazing Blade characters, and while Brave Lyn and Regular Ninian are technically free and are good picks for this map, it's not going to be enough to win you this one. It doesn't help that most of those maps either have That One Boss or is counted as That One Level. If you want those 20 Divine Codes, you're going have to earn them the hard (and sometimes expensive) way.
- A dishonourable mention goes to the Limited Hero Battles selection in Sept 2023, which features the Dual Boss of Gotoh and Fomortiis for one of the maps. Already a pretty tough map with both Fomortiis and Gotoh's forces advancing on you from both the top and bottom halves of the map, but which game are you limited to for this? Engage. The amount of free units from Engage at the time can be counted on one hand note . Sufficed to say, if you didn't summon for any of the other units, including Legendary Female Alear whose banner was expiring right around the time of the map's release, then you can just say goodbye to those Divine Codes.
- The Hall of Forms chambers 21 - 25 definitely qualify as this. Added alongside the first batch Thracia 776 units for this game modenote , some people have considered these levels to be extremely unfair because of the difficulty of a lot of the units. All of them end up becoming a game of relying on the map placement, because almost every unit there, even low-tiered ones (especially compared to the Tempest Trials and Forging Bonds), turn into Demonic Spiders, even if your units are around their level range. Fortunately, the only real reward there are Epherma Codes, and each of them give you an extra Forma Torch each, so if you were lucky to beat each chamber, you can use those chances to try to luck yourself out of the upper ones or try to rely on luck to get a better skill or merge your hero, and with the July 2020 Hall of Forms onwards cutting all the Book III heroes onwards from being generated, clearing those floors will be much easier with less Demonic Spiders plaguing the higher floors now, even with their refined weapons.
- Some of the Fluffy Fur Tour quests released in February 2021. All of the quests have you beat certain chapters from the Story and Paralogue maps which focuses on the early Beast units on Lunatic difficulty while also keeping all your units alive and enforces Character Select Forcing. Most of them are easy to beat, despite the restrictions, such as using only 4 Cavalry units for Book III Chapter 4-3. However, some of them are nearly impossible to beat without either using premium units or using Light's Blessings. For example, you must beat Book III Chapter 3-2 using only Red units, the same one which include Regular Naesala and Regular Leanne, whom the former is a strong Blue Flying Beast unit and the latter is a Colorless Flying Beast dancer that gives a great buff to Naesala, and beating Paralogue 41-3 with only Axe units, the same one which includes the New Years variants of Lethe and Selkie, both powerful Beast Cavalry units, as well as ranged Red units Anna and Eir. To add insult to injury, most of those rewards of those difficult quests are minor, with the only one giving a major reward from those difficult restrictions being the Book III 3-5 quest using only Sword units (the one with Hel, Regular Tibarn, Regular Nailah, and Regular Leanne), which rewards 1 Orb. It's telling that with the sequel quests, the Fall Fluff Tour in late September 2021, gave a much more forgiving requirement with it only needing at least one unit to fit the criteria rather than all four heroes, knowing that the devs realized that some of those Fluffy Fur Tour quests were very unfair to complete.
- The Defeat Veld's Grand Hero Battle with only Cavalry quest on Lunatic in November 2021. Already considered That One Level, but using any cavalry units at all is the worst thing to do beating this normally, as not only the area is littered with trenches, but all your units are separated behind those trenches with two of them being stuck behind breakable walls as well while the enemy has nasty movesets and Veld's Petrify debuffs one (or possibly more) of your units with [Gravity] and -7 Atk/Spd for the first 5 turns. Without using any premium units, it's going to be hell just to get that 1 Orb in a limited time frame.
- Maps like the Bound Hero Battles reruns usually have quests that involve bringing two of the three Askr Trio (Alfonse, Sharena, and Anna), and forcing you to win the two required, and also have them kill one of the two specific units on it to get the Orb rewards. These quests are widely hated because all three units are not very good and can't keep up in the games changing meta, and yet the game expects you to throw them into battle and somehow win with half your team handicapped. Even if you invest in them, they often can't win simply because of how powerful the enemy is. For example, the "Bound Hero Battle: Fallen Ike and Fallen Julia" rerun requires beating it on hard with Alfonse and Sharena, with Alfonse having to kill Julia, and Sharena needing to kill Ike, something that is nearly impossible to do because of how overpowered said enemies are. Of the quests, most just skip those two types of quest because of how frankly demanding it is.
- Fully completing a characters Forging Bonds Friendship is a tedious part of the mode that some players admit to never doing. You have to get several thousand points to fully clear out the rewards, across four different characters, while dealing with each hour having a different character be given a boost that can hardly feel like it works. While the rewards for doing so are good (both normal and rerun Forging Bonds), the tedium of doing so is enough that some only do enough to get the Summon Ticket, then only do it once a day for the daily reward because of how much grinding you need to get all the rewards.
- One of the most tedious examples of this is grinding favor in Summoner Duels to earn all the rewards. In this game mode, you fight in real time against another player for five turns, with each player having five units and five actions. They alternate actions whenever they move a unit, and they need to either have two or more units in the capture area than their opponent or defeat their foe's units to earn the most amount of points to win. Because of the real time nature of this game mode where you have a limited amount of time to act combined with the fact that every action counts, this game mode quickly becomes mentally draining. While there is a special weekend bonus that lets you earn ten extra favor if you manage to score at least one point in a match, you still need to score a point to begin with, which might not always be possible if the other player is hypercompetent and has a fully optimized team for this game mode. There's also the fact that connection issues on either end can severely interfere with matchmaking and completing matches, making things even more drawn out. All of these reasons are why the Summoner Duels game modes have a low player count relative to the total number of players.
