Well, talking about our flaming friend, to have an easy life in there, you should start doing those things : DEACTIVATE target lock ON, set a specific Chat Filter for the fight showing only Enemy Actions, and specially dont rush doing WS, because of animation lock.
there is 5 Phases in this fight:
1- he does normal attack on the tanker
2- (75% hp left) eruption (crack that explode after 2-3 second), jump+rush (he jump on the edge and do a rush in middle of arena it can kill you so NEVER be in middle), Vulcan Burst (AoE blowback action impossible to dodge it does 500 to 600 dmg) or Incenerate ( front Flame breath directed on tanker does about 1000 1200 dmg) Radiant plumes (plumes allover the arena tanker must be in proper position to make a right plumming since, plumes are dependant on ifrit position)
3- (50% hp left) Ifrit is enraged, glows and he does close range AoE attack 300 per hit, (thats why LNCs are favorite since can avoid those AoE) and same actions as phase 2 just now he do 3 eruption in a row instead just 1
4- 25% hp left he Summon Infernal nails, Quickly you gotta kill at last one nail to cut by half Astral Flow dmg HELLFIRE(if u dont kill even one nail you will get hit by 9999 dmg) after 60 second he summoned nails, he will jump in middle to do his astral flow you should use Sentinel(GLA22) to cut by half the dmg of it, about 1800 dmg. P.S. other Ifrit's WS will be same as phase 2 until HF
5- 25-0% hp left he will do same ad phaze 3 but now targeting multiple target whit Eruptions, must be calm and take the time to kill it NEVER rush in this phase