What makes Summon skitterbots so good?(dark's questions 2)

Why do alot of guides want you to use summon Skitterbods? It looks like it only works for mines.

they reliably shock and chill

The shock alone is 17% increased damage taken (at least vs single targets) and it chills too. It's even better with cold damage where you can link it to bonechill. With bonechill linked to a lvl 21 skitterbots it'd provide 34% increased cold damage taken for 42% mana reserved. Not to mention a 16% chill.

Not to mention they are immune to damage. It was quite a shock to know you could turn them into two indestructible walking fireball with Infernal Legion.

Furthermore, auras make an appliance of shock/chill easier even against bosses, so that resources that should be spent in increasing damage output for apply a meager shock/chill, or their duration, in merely increasing their effect

Last, if you really feel like that, the new Unique Ring can turn one of those auras in a Blasphemy-like cursebot, at the cost of one of your fingers

So the infernal legion thing? Does it still shock and chill with it?

Short answer, yes.

Long answer, read the skill description.

Keep in mind the 130% mana multiplier affects the 35% reservation cost (will be 45.5% mana). The only possible reason I can think of for using this combination is if you want a source to burn enemies but not deal any fire damage yourself. The damage is negligible, so it would be used exclusively for the burning effect.