Five mana to gain control of so many creatures is an incredible deal, and while you cant use those creatures to go after their former controller, you can certainly make use of them to take out another player
On foil cards it pops even more, leading to this treatment being a stand-out for me
Relegating Ambush solely to blocking and making it cost four mana just makes it unplayable for all but the most niche of battlefield states
It feels good to outright kill something with it, but it feels even better to put it on a creature that doesnt die because the Aura usually does enough to make that creature irrelevant while it also starts quickly pressuring your opponents life This is a pretty nice sacrifice outlet, and Black in this format has access to many rat tokens that will feel particularly good to sacrifice to this You cant build a dedicated discard deck in this format Paying a total of 8 mana for an extra combat step a good way to lose
By contrast you essentially never cast Boon of the Wish-Giver
When he attacks, he puts a +1/+1 counter on every Vampire you control, turning your board of small tokens into a game-ending army