Your Arcane Barrage and Ice Lance spells will strike up to 4 additional targets within 10 yards of the primary target for 50% of their damage. In addition, your Pyroblast spell will explode on impact, dealing 25% of its damage to 4 targets within 10 yards of the primary target.
Master of Elements
Arcane: Your Blizzard spell becomes Nether Tempest. Allows you to summon a Nether Tempest at the target location, which will deal X Arcane damage every second to three targets within 10 yards of the Tempest for 12 seconds. Nether Tempest damage is increased by your Arcane Charges, and will consume all Arcane Charges. Up to three Nether Tempests can be active at one time.
Fire: Your Blizzard spell becomes Leaping Flame. You launch a gout of flame at a target, dealing X Fire damage and then jumping to a nearby enemy target within 10 yards, never hitting the same target twice and hitting up to a maximum of 20 targets. Leaping Flame's damage is increased by 50% if you have an a Fire based damage over time effect active on the target. Leaping Flame requires Hot Streak to cast.
Frost: Your Blizzard spell's damage is increased by 25% and no longer needs to be channeled, but has an 8 second cooldown. Furthermore, casting Ice Lance while Blizzard is active will cause the Ice Lance to strike all targets affected by the Blizzard, dividing damage between them.
1.2% of Base Mana 40 Yard Range
Instant Cast 30 sec cooldown
Calls down a powerful meteor to strike an area, dealing X damage to all targets within a 10 yard radius of the meteor. The meteor's appearance and damage type will be appropriate to your spec.
This is just a concept, mind you. This tier is designed to offer different types of AoE improvement: Arcane Potency offers cleave damage, Master of Elements offers sustained AoE improvement, while Meteor would ideally offer burst AoE for dealing with large packs of low health adds.