Ground seal states that spells and abilities cannot target the graveyard but what about scavenge? It's already in the graveyard and its targeting a creature on the battlefield. The source is in the graveyard so can you cast the ability?
{Ground Seal} will not prevent your creatures from being scavenged...
RESOLVED
Scavenge targets from the graveyard. Not to the graveyard. It can work
This is actually the complete opposite way I've been playing