History GameBreaker / EtrianOdyssey

** The Medic's Immunize is a powerful resistance buff that reduces all damage by up to 60% at max level. If a max-level Immunize is boosted this damage reduction jumps to '''85%''', letting your whole team survive otherwise lethal damage and take ScratchDamage from almost everything else. Sadly, ''Heroes of Lagaard'' [[{{Nerf}} cut it out altogether]] (along with the Troubadour's Healing and Relaxing skills), and when it finally returned in the remake it would be dramatically nerfed in potency and only apply to fire, ice, and volt damage. The ''HD'' remake rolls back these nerfs.
** A CombatMedic build is most effective in this game, mainly due to common passives not scaling the same way across most classes. For nearly any class with the ATK Up passive, at level 10 it offers a 1.3x damage multiplier. For the Medic? The 1.3x mark is at level 3, and full investment is a '''3x''' multiplier. This makes the Medic hit about as hard as your actual frontliners, especially with a maxed-out Caduceus skill. Later games standardized the way passives scale between all classes, and the Medic's physical damage output took a big {{nerf}} and never fully recovered.

* Once you get to the 5th Stratum, money is no longer a problem, as just close by the Warp pole is a mining point that can be mined without fear of being attacked and making thousands of En per run with a team of Survivalists with maxed out mining. Like with Immunize, future games nerfed the gathering skills to prevent this from happening again, on top of introducing the risk of an ambush during the gathering process to punish gathering-specialized parties. ''The Millennium Girl'' rebalanced resource-gathering by adopting the system from the fourth game (one-use gather spots that restock on midnight) on top of repositioning the same gathering spot.

* Survivalists are not just handy for navigation and gathering -- they make for great DPS classes due to how strong Bow Attack Up, Apollyon, and Multihit are. Unlike most offensively oriented class, Survivalist only have a single attack up skills that boosts the power of Bow weapons but it scales up to 150% at level 10, the best of its kind. In general weapon boosting damage passive skills are much more impactful than the STR boosting damage skills. This works out in Survivalist favor who not only get a stronger damage boosting passive, they only need to invest 10 skill points to max their passive. Multihit gets a third hit at max level with no strings attached, greatly improving the DPS at that point and Apollyon is extremely powerful. Combined, Survivalist damage output is staggeringly high, being significantly more powerful than every other class bar Ronin. As with most of the powerful classes in 1, the Survivalist would suffer a heavy nerf coming into ''Heroes of Lagaard'', neutering its damage output while also removing the third hit of Multihit. Survivalist would then suffer from an identity crisis in terms of its roles until its return to form in ''The Fafnir Knight''.

* Gladiators have Berserker Vow and Charge. The former sacrifices a huge portion of HP for up to 90% damage boost, and the later allows them to do 260% extra damage next turn. Between these two skills, the Gladiator straight-up becomes the best class in the game for physical DPS, and is a staple subclass for anyone needing physical offense. No wonder any Charge skills in subsequent games don't reach similar damage multipliers outside ''Beyond the Myth''.

** Negotiation may seem counter-intuitive, until you realize that the healing scales with level. Remove a debuff and buff from level 99? Say hello to a full heal and 48TP! This is particularly helpful against bosses and [=FOEs=] who punish too many buffs.

*** Imperial + Hero. Give them Afterimage and you can get a second Drive in at no additional cost.

** The ''Origins Collection'' version of the game brings back what made ''[=EO1=]'' Medic so good after later games and the ''Untold'' remake toned the class down, and even buffs some of their abilities. Take Healing Touch, for example. In the original DS version, it requires so much investment for relatively so little gain, only healing up to each combatant's max HP times 40% at level 10. In the ''Origins'' version, it becomes a full party heal at level 3 for a mere 3 TP, and at level 5 it does the same effect but at ''1 TP'', basically giving you a free heal after each fight and allowing for much longer labyrinth expeditions than usual.

* The Sovereign's elemental Circles work akin to Fantasias (raising the party's resistance to an element while weakening the enemy's to the same element), do not occupy a buff slot, but only last a turn. In the Japanese version of the game, if multiple party members use it, the effects ''stack'', and this tactic, in addition to the above, is what allows the Fafnir Knight to take down the BonusBoss in one turn. The stacking does not apply in non-Japanese releases, though.

** Death's Edge is essentially a revised Revenge Curse. It gets a damage multiplier depending on how low each surviving party member's HP is, which can stack with Fortitude, a passive skill which boosts damage done while HP is under a certain threshold, and the aforementioned Overexertion. Careful utilization of damage tiles (which can never kill, only leaving members at 1HP) can result in damage that can one-shot the BonusBoss! The issue is keeping a party of {{One Hit Point Wonder}}s together until they can get there, but the result is high-risk, ''immense''-reward.

** Heavenly Aid is a charge skill with a rather complex mechanic - at the turn where it is used, Heavenly Aid would keep track of the percentage of HP the user had, and after healing is applied to the user, apply a damage multiplier based on the percentage difference between the two, applied every time the user is healed for the turn. When used at 1 HP, Heavenly Aid with full HP healing multiplies damage by around '''4 times'''. This can be taken further when used with Overheal, since the increased HP cap of overheal is treated as an extra percentage towards the calculation, treating it as if the target can reach 133% HP allowing as much as '''5 times''' damage modifier with Heavenly Aid. In theory, Heavenly Aid have near infinite potential to apply several instances of damage multipliers, only capped by the amount of healing applied to the user of the skill, and the damage taken prior to the healing being done. The user can then unleash a heavily boosted Titan Killer, Thunder Fist, or better yet, a well prepared Death's Edge to deal extreme damage to the target, sometimes able to even OneHitKill outright. The power behind Heavenly Aid is such that a well optimized Pugilist is able to one shot everything in the game, even the BonusBoss.

* The Ninja/Zodiac TP battery. The Ninja's class ability, Keburi no Sue, reduces the TP costs of all their skills by up to 9 points. Subclass to Zodiac and you can use the Dark Ether skill to allow a row of characters to use skills at no TP cost—this would normally cost 10 TP, but with Keburi no Sue, this goes down to the minimum of 1 TP. Now you can spam your party's strongest skills constantly at a cost of just 1 TP per turn. Want to have a pair of Zodiacs nuke the enemy with 60 TP Meteors every turn? Want your Gladiator to use the above Warrior's Might combo every random battle? Now you can! This applies mostly to the main game, though; once Amrita IIIs can be farmed in the sixth stratum, they end up being more efficient for long fights over dedicating a character to using Dark Ether and nothing else.

* Succeeding the Gladiators in the "staple subclass for damage" role is the Bushi, as their damage bonuses are very effective for minimal skill point investment. With a single point, their Blood Surge gives a long-lasting buff that doesn't consume a buff slot, drains miniscule amounts of HP and TP per turn, and gives a ''45%'' universal damage bonus. And that's before we factor in Charge, Defiance or their own Power Boost. Never mind the Bushi's own attack skills - imagine all these damage multipliers stacked on an [[spoiler:Imperial]]!

* Efficiency, available on Survivalists, passively doubles the strength of all HP and TP restoration items at max level. Combined with the Survivalists' high innate speed and they can easily be better healers than Medics as long as inventory space permits it. Somaprimes heal the party for 320 HP, Hamaoprimes restore 400 HP and 80 TP, and Amrita [=IIs=] restore a whopping ''200 TP''. Get it on a Grimoire and you can enjoy boosted item healing regardless of who's doing it. It's so strong that subsequent games nerfed this (and similar) skill's... [[{{Pun}} efficiency]], with ''The Fafnir Knight'' changing it to a buff and watering down its strength, and ''Beyond the Myth'' only having it affect HP restoration aspects of items.

* Hell Slash is essentially a stronger Warrior Might. It has its drawbacks in that the initiator has to [[GlassCannon abandon all armour for maximum damage output]], the number of chases is capped, [[FriendlyFire and it can chase enemy attacks]], but a total of 2400% damage from the physically strongest race with the strongest weapon class is nothing to scoff at. And this is before factoring in effects like the Pugilist's buff and the damage you've done from your other attacks.
** Hell Slash is a little [[DifficultButAwesome tricky to exploit]] until you understand its rules to maximize the number of hits it delivers. One of the most convenient ways to maximize it is to combine Grave with Fierce Shield off two Necromancers get the Wraiths to [[TakingTheBullet tank for the party]], counterattack three times for each hit, and get the Masurao to pile on for each counterattack. The drawback here is that you're dedicating a significant portion of the party to this strategy.

* The Ninja/Zodiac TP battery. The Ninja's class ability, Keburi no Sue, reduces the TP costs of all their skills by up to 9 points. Subclass to Zodiac and you can use the Dark Ether skill to allow a row of characters to use skills at no TP cost—this would normally cost 10 TP, but with Keburi no Sue, this goes down to the minimum of 1 TP. Now you can spam your party's strongest skills constantly at a cost of just 1 TP per turn. Want to have a pair of Zodiacs nuke the enemy with 60 TP Meteors every turn? Want your Gladiator to use the above Warrior's Might combo every random battle? Now you can!

* Swashbuckling. At first, it appears AwesomeButImpractical due to requiring eight points in both Rapier and Gun, but the surprisingly very high activation rate makes it worth it, even without Warrior's Might. Once you have it, any skill that doesn't have some form of utility or overwhelming power like Meteor or Nine Smash automatically becomes a waste of skill points and TP.

** The ''Origins Collection'' version of the game brings back what made ''[=EO1=]'' Medic so good after later games and the ''Untold'' remake toned the class down, and even buffs some of their abilities. Take Healing Touch, for example. In the original DS version, it requires so much investment for relatively so little gain, only healing up to each combatant's max HP times 40% at level 10. In the ''Origins'' version, it becomes a full party heal at level 3 for a mere 3 TP, and at level 5 it does the same effect but at ''1 TP'', basically giving you a free heal after each fight.

** The ''Origins Collection'' version of the game brings back what made ''[=EO1=]'' Medic so good after later games and the ''Untold'' remake toned the class down, and even buffs some of their abilities. Take Healing Touch, for example. In the original DS version, it requires so much investment for relatively so little gain, only healing up to each combatant's max HP times 40% at level 10. In the ''Origins'' version, it becomes a full heal at level 3 for a mere 3 TP, and at level 5 it does the same effect but at ''1 TP'', basically giving you a free heal after each fight.

* The original version's and ''HD'' remaster's [[TheMedic Medic]] is easily one of the most overpowered classes in the game, and perhaps the most powerful healer class across the series:

** The ''Origins Collection'' version of the game brings back what made ''[=EO1=]'' Medic so good, and even buffs some of their abilities. Take Healing Touch, for example. In the original DS version, it requires so much investment for relatively so little gain, only healing up to each combatant's max HP times 40% at level 10. In the ''Origins'' version, it becomes a full heal at level 3 for a mere 3 TP, and at level 5 it does the same effect but at ''1 TP'', basically giving you a free heal after each fight.