They work with all the creature-cheating tech youd expect in a Vintage Cube, and Summon: Knights of the Round and Summon: Bahamut work particularly nicely with such effects
The fact that all three are steeped in fantasy, and D&D and Final Fantasy are both role-playing games, and that Final Fantasy is the latest set are all solid reasons for why the quality here is by and large improved, but I'd actually argue there's a far simpler explanation
Mirror Entity: Absurd fun, enough said
If more than three other nontoken permanents you control leave the battlefield simultaneously, that choice is made only for the first three
Pippin, Guard of the Citadel By now we all know just how powerful Skrelv, Defector Mite is, and I think Pippin, Guard of the Citadel is arguably better