That's pretty much what a Controller is supposed to do: make your encounter into his encounter: thanks for showing up, please take a number, we'll kill you shortly.
Grasp of the Grave is a Daily power, so he shouldn't be busting it out more than once every four encounters (or so). When he does, it should make a huge difference in the fight -- that's what Wizard daily powers are like, in general.
Anyway, the standard anti-Wizard tactic holds across all editions: do not bunch up. If you assume "fireball formation", expect to be targeted by some area nastiness.
Cheers, -- N
PS: Of course, if you don't bunch up, expect to be targeted by some Striker nastiness... PCs are just nasty all around!