I have the skeleton of an idea for doing DW summoned creatures something different than the summon monster spell, more of a ritual.. I only own the core book so keep that in mind I’m not familiar if this is already done.
Player rolls and gets x number of holds based on the roll. The player then can spend holds to summon a type. Weaker cost less and strong creatures cost more.
So for example a necromancer could spend 2 holds to summon 2 skeletons or spend 2 holds to summon a single zombie.
On subsequent turns holds can be spent to activate the summoned creatures to attack and do other things. When the last hold is spent the creature leaves/blink sout/falls to dust.
On a failed roll maybe something is summoned but it attacks the summoner.
Yes this idea is based on the druids shape shift in a way.