borderlands-2
I am fighting the warrior right now, and as with some YouTube videos I have seen, the critical location for it is where the warrior's stomach is.
However, whenever I aim there, it never gives me a critical. Is there a specific spot or any gun requirement for getting the critical on warrior?
User Zikel, in the /r/Borderlands subreddit has tested Critical Ascension and came up with the ff. results:
You start losing stacks after 6 seconds.
You lose 1 stack per second.
Switching weapon, opening a menu (map, inventory, quest log, etc), using a vending machine, talking to a quest giver and dying instantly removes all stacks.
You can melee, throw grenades and sprint without losing all stacks!
Critical hits multiply the weapon's damage by two factors: first, the critical multiplier of the weapon type; second, the sum of all bonuses to critical hit damage (usually from abilities, but also from sniper rifles and a few weapon parts).
CriticalDamage = CardDamage × CriticalMultiplier × (100% + BonusA + BonusB + BonusC + ···)
Example: If Zer0 has five ranks in Headsh0t (+20% Critical Hit Damage) and is using a Jakobs sniper rifle (+160% Critical Hit Damage) that is listed as dealing 150 damage, then a critical hit will deal 150 × 2 × (280%) = 840 damage before being modified by elemental effects.
Weapons with the effect "Deals Bonus Elemental Damage" apply their bonus damage after the critical hit damage is calculated. That is: bonus elemental damage is not multiplied on a critical hit.
Weapon parts that contribute to increased critical hit damage:
When a weapon card says "+X% Critical Hit Damage," that value indicates the total effective multiplier. For example, a non-Jakobs pistol that says "+8% Critical Hit Damage" is actually reflecting the increase from a Hyperion barrel; the multiplier of 2.15 corresponds to a total effective increase of 7.5% (rounded to 8%); the weapon doesn't actually have a built-in critical hit damage bonus (like sniper rifles do). Similarly, if a Jakobs sniper rifle says "+180% Critical Hit Damage," that means the total bonus is +180%, not 180% on top of the base 160% that all Jakobs sniper rifles have.
Critical hits in melee inflict ×2 damage. Weapon or skill critical hit bonuses do not increase this any further.
Source: Borderlands wiki, "Critical Hit (Borderlands 2)" article
More detailed reading: Comprehensive Guide on How Critical Hit Damage Works in Borderlands 2 (Gearbox Software Forums post)
Best Answer
His crit spots are his Heart, his mouth and his...ribs? on his sides.
Here he his with a hole in his heart, taking some crit damage:
I tried to get a good pic of his ribs/side weak spot but they didn't come out clearly.
All crit spots save for the mouth are covered by hard, destructible rock; they're pretty noticable and just scream "weak point". Keep shooting them and they'll break, showing liquid lava underneath. All of his crit points are lava. His mouth isn't armored, but it's much harder to hit as it's always moving and nor always in an easy to shoot spot. I think, but I'm not sure, that his mouth takes more damage from shots than his heart. A good sniper can get a few good hits in there, but otherwise I wouldn't recommend it.
Note that the armor covering his heart and arm weakpoints regenerates every time he goes in the lava, which he does after taking so much damage. After you break the armor over his heart he'll go back under the level soon, so be quick. If you're precise and break just one chunk of armor and keep hitting the weak spot you'll have more time to deal critical damage than if you break all the armor around his heart, so be precise if at all possible.
Not some weapons like rocket launchers and other splash-damage weapons won't crit. Try a sniper rifle to confirm that you're getting crits. If your weapon isn't capable of getting critical hits, I recommend switching to one which can. Warrior takes significantly reduced damage anywhere but his crit spots, and even direct hits on his weak spots with non-crit damage won't hurt him much.