Anytime this kitty attacks, each creature you control with a power larger than its base power gets +1/+1 counters equal to the difference
This results in an obscene amount of mana generation, and Urza even comes with his own handy mana sink to use that mana, casting random free spells from your library
In many cases, this refunds the full cost of the spell or more, and against mana rocks, it often generates a tempo swing
If Thancred Waters leaves the battlefield or you lose control of it before its triggered ability resolves, the target legendary permanent won't gain indestructible at all
[-3]: Return up to two target land cards from your graveyard to the battlefield
The cardstocks construction also contributes to its durability, making it a reliable choice for products that require longevity and frequent handling