For starters, you gain one lore whenever its exerted, and on top of that, its an Evasive card, meaning few others are able to actually challenge it, which is crucial when it comes to climbing the ladder to twenty lore
Probably the most common cost for an activated ability is to pay some amount of mana, so most instances of paying mana are to activate an ability
I have now successfully Top 8 two SCG Opens and achieved a Grand Prix Top 8 at GP Pittsburgh last year
Melek, Izzet Paragon can let you cast one from the top of your deck, overloaded or not, and copies it if you do
Baboon Spirit Cards that can flicker on demand, like Baboon Spirit, are very strong, but they fall behind cards that blink on demand, like Eldrazi Displacer
Heres a big mana deck akin to Tron but that isnt bottlenecked by having to play all colorless cards