Mirror Entity Speaking of cards that have seen competitive play, the Mirror Entity was a staple of kithkin aggro back at the beginning of the now-extinct extended format
This means for just one mana, it can crew a Vehicle with a crew cost of four
Biotransference doing the organic-to-machine conversion is the flavor bonus on top
For example, in a game of Mystery Booster 2 Limited, Toralfs Disciple can conjure Lightning Bolts into your deck, even though the card Lightning Bolt isnt found in Mystery Booster 2 and isnt normally legal in the Limited format
A few turns later, I managed to clean house on their side of the board with a combination of instant effects and character challenges, overtaking them for the win
The rules say that when you resolve a planeswalker, say Jace, the Mind Sculptor, you put 3 loyalty counters on it as it enters play