With their help, you will always know when your cards have been affected by the enemy (for example, a loss of health or life)
Crucially, unlike the original three titans, it can be reanimated from the graveyard, opening up playability in more archetypes
The format is also very well-defined since Dredge and Mishra's Workshop decks are key pillars of the format that are too powerful to fight against unless you bring the right amount of disruption
I suppose the actual play for Ukkima would be to protect it from targeted removal with Ghostly Flicker-type effects, but I personally hate a strategy that relies on my opponents interacting with my board
However, there are plenty of options other than Rayquaza and Giratina to enjoy, like Mew and Ho-Oh
Following the massive success of previous sets such as OP-05, OP-09, and OP-13, this new expansion is already generating major hype across both competitive players and collectors and for good reason