Ice Guardian? Sounds like you saw one of the Minions. Little booger. Squeals like a cat when you plink him? Minion. Big, Frosty Frog-like dude with glacier-calved icebergs for claws that chews Indy in two or three stomps? Guardian. Major difference. Many minions. Only one Guardian.
The point of the level is to get Urgon's part of the infernal machine. The Guardian, natch, guards it. Having it lets you kill the Guardian, though not instantly. You still have to do a little running and medicating between zaps, especially if you zap too often and the Aetherium hurts you.