Is Hildryn really that bad against Infested?

It’s a weaker matchup for Pillage, not a case where Hildryn stops working. Pillage gets much less shield refill when enemies have little or no armor or shields to drain. It can still clear status effects, but that won’t make it the same kind of sustain tool it is against other factions.

Your weapons and Balefire still give you ways to deal damage. Think of Pillage as less central here, and watch your shield pool rather than relying on it to refill every cast.

You don’t have to keep Aegis Storm active just because it’s available. If its shield cost is making the mission harder, use it selectively and focus on your weapons instead. Infested reduce the value of some of Hildryn’s usual tools, but that doesn’t make the whole frame useless.

Pillage can still be worth casting for its status-clearing effect, even when there’s little to strip. Just don’t expect it to refill your shields as reliably as it does against enemies with armor or shields.