Hi.
I tried creatures with Mobilize in combination with Ojer Taq. Ojer Taq was transformed into a land. I attacked with Dalkovan Packbeats (Mobilize 3). Then at attack there were four creatures attacking the opponent. While being in 2nd Main Phase, I couldn't activate: "2W, tap: Transform this land. Activate only if you attacked with three or more creatures this turn and only as sorcery.". I play MTG:A on PC.