­Traumatize + Undersea Current

Mill thirty cards, and a nasty Winter Orb ish.

Well, that's an obvious mash - winter-orb the library.

So much a win condition - pile on the limitations; it's a small creature, it's an enchantment. And of course you can still use card-search to bypass it. Forced-looting would be a devastating combo - so I'd better price this quite high.

Legendary creature - mythic. Easy.

Oh, cool. It might not be printed like that because if you get into a stall, you'll never get out of it, but I like the idea and I love the flavour.

Hmm. Yes, Possessed Portal would at least eventually force itself to die. This might be a bit prone to "oh, I guess the game is a draw then".

Mmm, it does a bit. It's got a built in sacrifice (you can just attack with it, and winning that way would be hilarious) but if you fear you'll lose the stalemate you might not invoke that.

Cumulative upkeep would, sadly, be needed I fear.

Wouldn't Winter Orb the library be more like "Players draw one card during their draw step." :D

Well, that's true. But also somewhat pointless.

I did consider "Players may draw no more than one card in their draw step, and none at any other time." but is seemed like a bit too specific a hoser to be interesting. (Though still good with forced-looting)

The Stasis approach would be "At the beginning of your upkeep, sacrifice ~ unless you discard a card".