Rituel
Exilez toutes les créatures. Incubez X, X étant le nombre de créatures exilées de cette manière.
If Sunfall resolves but doesn't exile any creatures, you'll incubate 0, creating an Incubator token but putting no +1/+1 counters on it. It will still have the ability to transform, but you might need to figure out how it's going to survive first.