Put Garuda at the place where you are when you enter into Ifrit arena. Since you normally dodge the eruptions by going right (if the debuffed healer is at the left). Garuda won't take any eruption damage. When Ifrit dashes... Garuda won't die even if she gets it by all dashes and you can cast 1-2 Sustain while dodgin'. WHen Ifrit do his special attack, bring Garuda in the middle so that she takes all the heal and put her back at her place. Voilà.