Knight of the White Orchid has helped significantly with not falling behind against Gideon, Ally of Zendikar, but it is difficult to win when they follow it up with Wingmate Roc
You can trigger it during your opponents turn, too
Don't get left in the dark
Those who played that set, or who encountered the odd copy of this card in Modern or Legacy thereafter, know of its unassuming power
Dark Confidant has also been a long time Plan B for combo decks, whether in the sideboard or the maindeck, such as Paulo Vitor Dama Da Rosas Dark Depths deck from Pro Tour Austin: Creatures (11) Lands (24) Spells (25) Dark Confidant is great for finding combo pieces and great when you dont assemble the combo
It got a pretty big mana cost attached to it, but you get to exile any nonland permanent, and you can put this card in any deck