Ive got four different answers for you, and the first one has been propping up Delver of Secrets since 2011
Suddenly, Balance decks started popping up along the East Coast that were capable of dropping their entire hands by turn two plus casting their namesake Balance to strip out every card in their opponents' hands
Plus, activating her commander ninjutsu ability will only ever cost one blue and one black mana, as commader tax doesnt affect abilities
When an opponents effect would remove one, you pull from the top of your Life instead
In the mid to late game it allows you to search for anything in your deck other than the 9 green creatures
Tourach, Dread Cantor Tourach, Dread Cantor requires a heavy black deck to function due to the color-intensive kicker cost, but you get a powerful three-for-one if you manage it