Summon nasties

Summon nasties is a monster spell, able to be cast by level 16 or higher spell-casting monsters.

If you are in Gehennom, there is a 1/10th chance that a demon is summoned. Otherwise, nasties will be generated around the caster untill a random number between one and one-third your experience level of nasties that are either neutral or of the caster's alignment are generated. There is a restriction that spell-casting monsters that do not have a level less than that of the caster cannot be generated by these means.

Monsters summoned in this fashion respect genocide, but not extinction.