Alhammarret believes you're ready for a real mission. As an arbiter for peace, he needs up-to-date intelligence from the front lines. You are to infiltrate a rebel camp, use your mind magic to defeat the guards, and learn their battle plans.
The Trovian Separatists have some powerful cards, but fortunately they only have one copy of the most troublesome ones. They only have one flying creature (Nightmare), so the basic strategy is to attack with evasive creatures (Phantom Warrior, Phantasmal Dragon, Nimbus of the Isles) while holding down the ground with your other creatures.
Be aware of Mutilate, even though the Separatists only have one. If you have control of the board, it may be wise to hold back other creatures unless you're also prepared to Cancel a Mutilate (or of course if they've already played it).
Jace's deck now has three copies of Sphinx's Tutelage, so mill is now another more viable route to victory, but because Jace has few answers to the Separatists' powerful cards, with only three Cancels, and the Separatists have three Gravediggers to get back Nightmare or Squelching Leeches (which Jace can't effectively deal with when they're large), it isn't wise to force that plan.