I dont really know what to think of it. It is an awesome spell, but it really really does not belong there, it clearly didnt have any other empty space left xD
A Necromancer itself would not benefit much from it, but I guess if your party has Cassandra, Varric and Cole as I intend, their dps is going to sky rocket.
From time to time, Dorian will come to say hi, so then I will just switch Haste for the Mark of the Rift.
Now that I remember, from the videos we saw that Inquisitor Tree. It had only 2 abilities by that time, Mark of the Rift, and a passive which reminded me of "unity" from Mass Effect. The tree said something like inspiring your team since you are a leader blah blah, so I expect some party buff.