Afterlife much? Yeah, such straightforward forced creature saccing in white (that isn't centered around "balancing" effect) needs to be adjusted to. Forcing to sac attacking creatures is something that white does time to time though...
Notable similarity with Pack Hunt. This is much harder to assess since you can search for multiple different creatures and also those that you share with your opponent. So perhaps it's closer to Congregation at Dawn.
Considering the creatures are put on top of library it seems unlikely this would do anything that broken... Going with Elvish Visionary and Wall of Blossoms for example seems nice but not backbreaking.
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lands now ETBT
"for three land cards" >> "for up to three land cards"; compare Nissa's Renewal
That's quite brutal, indeed. A lot better than first strike. Reminiscent of Laccolith Grunt, but normally even better.
Damaging just the blocker has been done a few times: Assembled Alphas, Acolyte of the Inferno, Flameheart Werewolf, Inferno Elemental. (And there's also Goblin Swine-Rider for the more indiscriminate version.) Hitting the player has only been seen before on Assembled Alphas, I think, and that's got the "blocks or becomes blocked by" line. Makes this a bit reminiscent of Lone Wolf / Thorn Elemental.
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I can kinda see white getting this; but it would need some kind of condition really. Sacrifices a tapped creature, maybe?
Though ironically that would also make this somewhat better most of the time; so maybe not that.
How about the creature comes back when the spirit dies?
Afterlife much? Yeah, such straightforward forced creature saccing in white (that isn't centered around "balancing" effect) needs to be adjusted to. Forcing to sac attacking creatures is something that white does time to time though...
Notable similarity with Pack Hunt. This is much harder to assess since you can search for multiple different creatures and also those that you share with your opponent. So perhaps it's closer to Congregation at Dawn.
Considering the creatures are put on top of library it seems unlikely this would do anything that broken... Going with Elvish Visionary and Wall of Blossoms for example seems nice but not backbreaking.