General Pet Things
Assault 1: Crimson Cyclone
Assault 2: Flaming Crush
Role: 3+ target AoE
Assault 1: Aerial Slash
Assault 2: Slipstream
Enkindle: Aerial Blast
Role: Survival & soloing
Assault 1: Earthen Armor
Assault 2: Mountain Buster
Mountain Buster is unique among the Egi Assault IIs in that it is the strongest EA for immediate AoE damage at 250 pet potency/target without falloff.
In comparison to Slipstream, it is always guaranteed to do 250 pet potency right away which makes it have interesting considerations to be used for AoE burst given that you can do 2 Mountain Busters within less than 3s for 500 pet potency/target total.
Conversely in 3 seconds two Slipstreams may do 150-250p total, the equivalent of up to just 1 Mountain Buster. Remember that for 2 Slipstreams to do their full potency per target it takes 18s worth of Gale Enforcer pulses (2 * 9s) with all entities remaining in the ground AoE radius.
This means that depending on how long multiple targets survive for, having Titan-Egi out briefly for 2 quick Mountain Busters can be the correct call for AoE burst before swapping to Garuda-Egi, even with the cost to pet GCDs from the swaps & especially if party buffs are present.
As always be mindful of how long add packs live for while thinking about your cooldowns.