This gives the player an advantage in that their opponent is forced to either damage themselves or allow them to recast a potentially game-winning creature
Creatures with this ability function similarly, leveling up as the cost is paid, but require Experience Counters, allowing them to be manipulated by effects like Propagate, and replacing their power, toughness, and abilities as they level up
The question for building the deck is if we want to go full mill as a win condition or just some incidental milling as a method of getting creatures into the graveyard to regrow with Captain Nghathrod
Wan Shi Tong, Librarian is a good flash threat in a longer late game, but its also good early since it draws you a card and you can return it to your hand via ninjutsu
They can be obtained early as Chapter 1, provided you can train an Orator to invite them, and they breed higher-tier members of their families that normally don't spawn at that stage in the game and often have abilities that are incredibly powerful during the early stages of Tactics
Planeswalkers are a good start, among other options