As her Revival Trance deck puts it, fill your graveyard and revive your fallen heroes. Put simply, Terra lets you return a creature from the graveyard to the battlefield at the price of 2 mana whenever she damages a player
For example, if you attack with a 5/5 creature with trample and it's blocked by a 2/2 creature, you can assign 2 damage to the blocker and 3 damage to the defending player
And it certainly leads by example: Vivi Ornitier basically ruined Standard alongside Agatha's Soul Cauldron and earned itself a rightful spot on the banlist
He competes with Mickey Mouse - Detective in the 3-ink slot but since he's inkable and quests for more and gives you that repeatable ramp effect, I think he may replace Mickey as the 3-drop of choice
In contrast, Souvenir Snatcher can snatch artifacts from your opponents, and and Cavern Whisperer can force them to discard
If you want to play black, you're going to need at least a couple of copies of Sheoldred for the sideboard