The Big Idea (Unstable) | Illustration by Bram Sel If a deck has more than 250 cards, MTGA will refuse to save the deck
The important line is at the bottom there, the third ability: 4, T: Copy target permanent spell you control (the copy becomes a token.) This might not be new new rules it might be that this was a lurking clause in the comprehensive rules at some point, not brought forward or presented obviously in some rules card or whatever
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
Getting Gravedigger in the command zone along with a cost reduction ability lends itself well to a creature-based graveyard strategy
Im just not sure all women are literally ten times more powerful in hand-to-hand combat than the king of the dragons
These are the cards you really want to see in your Sealed pool, or passed to you in Draft