You can kill each spider with 2 Lightnings.
Zap the first from afar, run a bit for the Cooldown to refresh, zap again.
For the Steel Wizards (the "machine gun" robots that shoots energy beams), you can either run back and forth at a distance, avoiding their energy beams, and zapping them at the intervals of their shots, or you can do the "cheater" and non challenging approach of using a lvl 1 shock imp summon that is 100% immune to their attacks.
For the spiders, you can alternatively zap them once at a distance and hit them twice with basic attacks, just know that with that you'll be hit once or twice, so be prepared to "tank" those in the chest. Have Mage Armor up, maybe you'd want Mage Barrier too (but I've done it all without it), but just pay attention to run away as soon as you destroy them, otherwise their self-destruction explosion may kill you (or hurt you badly).
Anyway, in the Ark you'll need to be pretty good with your positioning and movement. Just brainlessly standing still and hoping for the best wont do, you'll require some skill here (especially for Elementalist Mage)