The mana value restriction of 4 also represents that it is a basic item for reviving your party members, not a miraculous Lazarus stone
2021-03-19 If Containment Priest enters the battlefield without being cast, its ability won't exile itself
It's not as much of a jump as you get by Shifting a card, but it also doesn't rely on having specific cards in play and in your hand
The payoff of this meld pair, doesn't win the game on the spot, and I'd stress that to your Bracket 3 playgroup because while this deck puts together powerful cards, it is not optimized to be unbeatable, and more focused on a huge play with some Golgari death and graveyard interaction molded in
Technically, both cards can do the same theft effect with a small difference: The creature half can exile a card from an opponent's hand, and they pay its mana value to have Valki transform into it
Embercleave only technically costs that much because of its ability: it costs one less for each attacking creature you control