It's -1 to its toughness, which is worse than Animate Dead ($0.99 and 34,592 decks at EDHREC.com) which is only just -1 to power and has the same cost as Persist
These cards typically gain charge counters over time or through activated abilities, and later spend those counters to produce a powerful result
In order for it to generate advantage, we need to already have stuck a big creature on the board
First of all, when Regisaur Alpha enters the battlefield you create a 3/3 green dinosaur creature token with trample, so it's like getting two creatures for the price of one
Their ultimate is not only powerful, but its also quite achievable, should you ever need to use it
There are a lot of creature heavy decks in the cube