I think this has some possibilities to be fun, but also I don't quite know if it's that impressive
You see, when it or another Zombie enters the battlefield, all non-Zombie Creatures get -1/-1 until end of turn
Lethal Sting | Illustration by Randy Vargas Regeneration is an ability that protects your creatures from dying
It's also worth mentioning that since we are putting the card onto the battlefield, everything we play with Aid from the Cowl is uncounterable, which is very helpful against various control decks
Particularly in Commander, where the high bar set for aggro decks all but demands some kind of rapid multiplicative damage scaling, having all your creatures buff each other (for free!) is a true difference-maker
I wish it were a little cheaper so that you could spend more of the early game maximizing this ability