@HoffOccultist: A few handy Day's Undoing plays --
1. 'Walker synergy: With Narset, you draw, they don't. With Teferi, you can Days on someone else's turn.
2. Extra explosive starts: With fast mana and cheap stax pieces, sometimes the deck dumps its hand early before opponents can do the same. When you Days, you net 4-5 cards; opponents might only net 1-2.
3. Yet another anti-GY card: It's not the best, but sometimes that's still good enough
4. Everyone topdecks! This is a fringe play, but if you have
Omen Machine without Lavinia, you can Days to kill everyone's cards and put the table in topdeck mode.
Admittedly, the
Timetwistereffects are better in multiples, so Days Undoing gets a lot better if you also have
Time Spiral and the original.
Time Reversal and
Commit // Memory might be reasonable adds if you wanted to play a more 'twister loop style build.
@Spectrar:
I don't know if you really need Treasure Mage. The deck's pretty slow, so with its current tutors/cantrips you have a good chance of finding one or the other by the time you need it. The other two mages make the cut 'cause there are a lot of different early-to-mid game plays to make with them.
I blanked of Sea of Clouds. I'll edit it in.
@kirkusjones
Wow, that's really clever. I can't believe I didn't think of that... a friend and I were just talking about things you could do with Painter's Servant and Dream Halls. I don't know that it fits with this list exactly... maybe Lavinia + Dream Halls is the build with all of the Timetwisters, and you just play through your entire library repeatedly.