The option to run multiple legends in the command zone allows for a ton of deckbuilding flexibility
New players might come to Magic: The Gathering because they can have pretty foil cards of their favorite video game character, but older players might get tired of seeing their beloved game diluted by other IPs (a common complaint about Universes Beyond)
It's also good in places like game winning with creature heavy brews like Hate Bears, Blink, and Midrange that have loads of bodies
Even without these specific synergies, the card is just a solid grindy value engine, however, so the floor here is pretty high
When you cast Ulamog, youre not just putting a 10/10 creature on the battlefield
Then do it again.) When Roalesk enters, put two +1/+1 counters on another target creature you control