The extended buffed dots + extra Ruin casts adds about 500 Potency to the opener.
This is greatly increased by time sensitive skills such as Battle Voice Foes and Trick attack, as well as doubling the damage of a Poison Pot with Contagion.
How quick Garuda attacks at the start (ranged) + Foes offsets the Potency of Ifrits Enkindle/Extra damage.
Once the pet buffs are off and the slash/blunt debuffs are up you definitely want Ifrit out though.