Random Generator gave me Necro-Impotence and Possessed Portal. Sometimes I just tinker with a card until I find something I like, then find out that I'm not really near the source cards. Obviously, the Necro part is noticeable here... But Possessed Portal Seems very far away. Making it an 8-cost artifact, or adding something about each player sacrificing something would help, but I like where the card is. It's tough to nudge a card once you like it.

Also, strangely, I already got 2 black mythics (and one in the workbench). It's, like, the least needed color/rarity. So this card goes in the workbench. After the fact, I know think I should have found a way to make this card red so that it could hit the set. Maybe I will tomorrow. I'm sure those two cards can make something very different.

Nice effect. Could probably be a lot cheaper: 5 mana or less.

It's tricky. Not counting the untap thingy, this is roughly Yawgmoth's Bargain. When Bargain was around, you didn't really care about your untap step; You were going to win the turn you played it.

To be fair, that's 100% because Skirge Familiar is super broken. I don't think we print cards like that nowadays, and I think the untap thingy is rather restrictive. I can't imagine this being fair and costing less than 6, though. Cards similar to Vitalize or Early Harvest alone make me think that the untap restriction is only a restriction for the casual player.