"Disturb [cost]" means "You may cast this card transformed from your graveyard by paying [cost] rather than its mana cost." When you cast a spell using a card's disturb ability, the card is put onto the stack with its back face up
To put it in another way, it's basically assured to hit the graveyard within three seconds after being cast
Unfinity is the latest of MTGs Un-sets, which pride themselves on the preposterous - and while this set does have some cards that are legal in Magics eternal formats, for better or for worse, it hasnt toned down the nonsense
Ideally, the player will target one hostile creature with removal, then trigger Legolas' second ability to deal damage to a second target, creating a two-for-one.
Its definitely a proactive value card as opposed to surgical removal, so itll be build dependent
He can do this with his inbuilt prowess ability, but it's probably more efficient to suit him up with protective equipment that boosts his power incidentally