At this point most players will start wondering, "What do they have to stop what I'm planning?" Abeyance takes away all that worry, while greatly increasing the chance of victory during an attack (or defense) by preventing the opponent from playing "instants, interrupts, sorceries, or abilities requiring an activation cost"
The best Ninjas are always those with card advantage on their damage triggers, and while green is already overflowing with this sort of incidental card draw, Avenger could still sneak into some Standard lists
All the Eldrazi are popping off in some way, and that deck is proving super popular in the early orders, so it might be good that you can get Ulalek in Play boosters, too
Unfortunately, it cant really be counted as a good card, either