In addition to these combos there is a trait in water (Shards of Ice) that stacks vulnerability upon use of arcane spells (Arcane Wave and Arcane Blast). I try draw mobs to me, drop a Lava Font, shoot one with Arcane Wave and Arcane Blast followed by Flame Burst (for stacks of burning) and Burning Retreat. That mob is now down and I can work on the rest.
Also taking the trait Arcane Mastery means that Arcane Blast cooldown is now 14 seconds allowing it to be a regular combo finisher. This means that for veterans I can keep vulnerability up almost constantly using just Arcane Blast finishers.
The secret to using the staff is to know your combos and almost never rely of single spells.