Lightning bolt and Summon Death are the best way to deal with them.
Lightning bolt those outside, and once you get inside you can't use lightning bolt anywhere.

When inside: deal SOME damage to them, summon an area shield (E > Shift + right click) and up it's strength a bit (tapping space bar repeatedly while hovering over the shield) and use the Summon Death magick. It'll go after whoever has the lowest percentage of health, which is why you damage them. They're tough, but not invinible.

Screw it, I just hasted/teleported myself through half of the chapter now without bothering to fight them, until the lava bit where they no longer appear.

That's how I did it haha. I tried killing them for a while but it was just far too difficult, so scooting around was better haha

http://www.youtube.com/watch?v=Xf-a65P_C10

^^^^ Two new Challenge maps scheduled to be released on April 26th. One will be free, the other for $1.99. Not sure which I'd like, probably Caverns, though.

The yetis you mean? I couldn't get past those with teleportation since the screen locks. I just used rapid area of effect lightning and arcane which seemed to do the trick.

That bit with the elemental skeletons was awful. Not too hard to figure out of course, but quite annoying.

Downloaded the demo last night... what fun!

I'm just about to purchase the full game now.

http://www.pcgamer.com/2011/05/20/magicka-dev-diary-shards-shields-and-spam/

Looking forward to it!