FYI, If you're planning out your commander decks early, it looks like Toph, Earthbending Master, and Wan Shi Tong are fan-favorites for Commander leaders
Once your graveyard is nice and full of expended Necrons, you can use the Scarabs to exile them and build an army of evasive 1/1 fliers, giving your opponent a single turn to deal with them before you attack in the air, most likely for lethal damage
The Collector 3
If instead you accidentally said "At the end of turn" then your Amalgams wouldn't be in play until your turn 2's end step
What this doesn't include: Cards that only recur one creature to the top of library or hand for more than 1 mana, unless it's a land
Raphael, Ninja Destroyer Raphael, Ninja Destroyer is a sturdy 4/4 and gives you some mana storage