Since the given creature attacks the controller, they count as the defending player for, say, annihilator
You can play explore cards that let you hit your land drops more efficiently, it helps to play 3+ colors or expensive spells, it sets your graveyard for shenanigans, and much more
Spring Six mana for two cards late game isn't bad
Not going face is a shame but in most cubes creatures are sufficiently prevalent that you are fine with that limitation on your burn
One of the main considerations with a card like Permission Denied is that it can be difficult to hold up the necessary mana to cast it while still advancing your board
Strangely enough WotC decided not to give this Troll any kind of self-protection, as was the case with many other Trolls in the past