Summon Monster spell for the wizard

[QP Evergrande]

And obviously, the Staff of Cthulhu should make the spell summon stronger things, up to and including those eldritch things that flay you. Although to balance that, maybe the cooldown time on the spell should vary depending on what was randomly summoned.

Oh, and about those "harmless" creatures. They should sometimes spawn with diseases, which can be spread through biting.