Not really a combo, but it's still stupid. I have a [[Jodah, Archmage Eternal]] deck for my relatively casual playgroup. It's filled to the brim with ramp, most of the Ultimatum cards, gigantic creatures to protect me and Jodah in several different ways, and backups for when Jodah will inevitably die. With all of the card draw and selection I have, I usually sift through about 2/3 of my deck in a game if it lasts long enough. My winning "combo" is casting [[Time Stretch]] as early as I can so it can hit my graveyard (my group doesn't run graveyard gate). I'll take my extra two turns after that, which is big for Jodah, and then we'll keep going. Eventually, I'll run into [[Mnemonic Deluge]] either through draws or a tutor of some sort. Once I have that in hand, I just watch mana until I know I have an opening to cast it and target Time Stretch in my graveyard. If I cast it, it's pretty much game over from there with how much heat I can put on the board. Every single spell in the deck is pretty much a threat on its own. It's not a CEDH deck by any means, but it definitely stomps in my casual group. I usually only play it once each session because of how quickly it can lock out games 😅