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
Not only does he let your Defenders attack as though they didnt have Defender not only does he give you the damage according to toughness ability he also gives you a source of hand refill with his final ability
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
It's a very nice mechanic, as it grants these creatures a lot of flexibility
Redoubled Stormsinger can be an incredible card if you pay attention to sequencing