A hasty 22/22 with Annihilator 15 is generally enough to end a game
Thassa also works great with cards that have enter the battlefield triggers or might have other effects on them that might be preventing you from attacking or activating abilities
If that rival dies, Zenos transforms into Shinryu, Transcendent Rival, an 8/8 flier that picks a player, and if that opponent loses, you win the game
Even moreso when things like Gilded Lotus are also here to make ramping up that much mana easier than ever, surprisingly making colourless a force to be reckoned with in this set
One of the more numerous mechanics that isn't evergreen yet still able to boast a very significant percentage of those cards as having been used in cube and indeed still useful in cube
Then, any time, you can turn that creature face up for its disguise cost