If the top item on your sleeve checklist is aesthetics, Legions sleeves are the way to go
If your opponent mills your entire deck, you usually have until your next draw step to solve that problem somehow, whether that means winning the game yourself or finding a way to put cards back into your library
In general the higher the ink cost of the card, and the more unique the ability, the higher up the rarity chart it will go
If you're interested in creating your own holographic cards , QPMN provides a great resource on how to make holographic cards, including both DIY and professional methods
I just don't know the Assassin's Creed story and world well enough to feel confident in matching each of these characters with the exactly right Magic card
Just be aware that the quality of these templates may vary, and they may not be perfectly accurate