All-in-all, Tibalts Trickery is still a little too inconsistent to be banned, but Im always willing to be proved wrong when someone far more ingenious than I just trashes MTG for a couple of weeks with a new deck
Cost reduction will allow you to get cards like Karametra, God of Harvests, Reki, the History of Kamigawa, and Gandalf the White out early in order to capitalize on their ramp, draw, and synergy
Essentially, you cast Amulet of Quoz, sacrifice it after a whole turn, and bet the outcome of the match in a coin flip
You can cleave it as an alternate cost, and then you net a free spell for the turn, and I love it on an enemy's turn when you cast this for free, to bounce what your foe played and then drop a flash thing like Hullbreaker Horror or Ancient Stone Idol or you can just cast another instant that draws you cards
It's a very nice mechanic, as it grants these creatures a lot of flexibility