Well for one, currently Mana Crypt is only played in PO and Shops for the most part. A lot of decks have nothing to do with 2 colorless mana. And for a long time, Stax players would sometimes lose to their own Mana Crypt.
You can also look at old school where mana bases consist of City of Brass and people play Black Vise and Ivory Tower. The life loss is significant especially if it’s not helping you to cast Counterspell.
It seems much better in the premodern era but I can’t speak as to why it wasn’t played.
I would also ask @LieNielsen, which of those matchups is Omnath bad against? It's really just Xerox (which hasn't been very popular). Omnath is actually better than Mentor against PO and Doomsday because of the ability to pitch to Force and the cantrip, so it's rarely a dead card as opposed to Mentor, and I've found it to be circumstantially better than Mentor against the various Hogaak decks since your tokens can't always deal with the Trample. In any case, you aren't choosing between Mentor and this but having a card that has a comparable role to Mentor is certainly a boon for control decks in this metagame.
It wouldn’t be my first choice against any of those matchups specifically but I can acknowledge that it seems to be functional in some useful capacity in probably all of those matchups.
It just doesn’t slot into any good existing decks and the card isn’t powerful enough to justify a whole new archetype.
According to mtgoldfish the topdecks are bug, doomsday, PO, Xerox, Workshops, Dredge, etc. Omnath doesn’t fit into any of those decks and his abilities are not impressive in vintage for the reasons I mentioned.
Cool card. I don’t think it’s good enough for vintage and here’s why:
The self replacement is nice but you’re still just getting a 4/4 creature (without haste) so you’re not putting any pressure on your opponent with static abilities (like Lodestone) and there’s no threat of fast beatdown (like with Vengevine).
The first two landfall triggers aren’t that great. We already have Lotus Cobra to generate mana from landfall triggers and Lotus Cobra sees no play. You just paid 4 mana to cast Omnath, so unless your deck is full of high casting cards, there might not be anything to spend the mana on.
The 3rd landfall triggers requires extra stuff to pull off and it’s not even a relevant ability in all matchups — In most matchups.
So in conclusion all you’re really getting here is a cantrip 4/4, which is good enough for limited, but not Vintage.
I think it’s probably good enough in Standard as well.
Thanks for the responses! I can see why this planeswalker may not make the cut except for as a fringe card drawing spell. I admit that when I saw it, I was thinking about all the other great 3 mana Planeswalkers, not realizing that this Jace might as well just be a Jace Beleren.
I feel like this could still be an option along side Jace Beleren for hitting islands in a Stasis deck, but that’s pretty far from the mainstream competitive metagame.
Jace, Mirror Mage 1UU
Legendary Planeswalker — Jace (Mythic Rare)
When Jace, Mirror Mage enters the battlefield, if Jace was kicked, create a token that's a copy of Jace, Mirror Mage, except it's not legendary and its starting loyalty is 1.
- 1: Scry 2.
0: Draw a card and reveal it. Remove a number of loyalty counters Equal to that card's converted mana cost from Jace, Mirror Mage.
This card seems like a solid 3 mana planeswalker in vintage due to the relatively low converted mana costs of cards in Vintage decks like Xerox or Bug. Even hitting a Force or DTT doesn’t seem like a terrible trade off. It also has the upside of being able to be kicked for additional card advantage.