That's a ridiculous amount, and quite honestly, a lot of this list is going to be chosen by my own memory and personal feelings
Champion Changelings: Changeling Titan , Changeling Berserker , and Changeling Hero Changeling Berserker, Changeling Hero, and Changeling Titan can each champion each other, and create a loop of enter the battlefield triggers
Goatbots suggested swaps feature This feature suggests cheaper versions of cards you own, potentially allowing you to make more cost-effective trades and increase your profit
Both created interesting situations where opposing players could potentially get themselves into a lot of trouble if they cast a spell and opened up the opportunity for their opponents to counter it
From here you can sacrifice a larger mana value creature to return the recursion piece, and use Deathrender to cheat it out