Pyrocosm

In the Arcane Mage talent tree, Pyrocosm sits in the Sunfury hero talent tree, row 3 of 5. It is a single-point node.

Connected above

The tree draws a line into Pyrocosm from Glorious Incandescence.

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  Glorious Incandescence

  Generating a Spellfire Sphere causes your next cast of Fire Blast to call down a storm of 4 Meteorites on its target. Calls down a meteorite which lands at the target location after 3 sec, dealing (102% of Spell Power) Fire damage to all enemies hit, reduced beyond 8 targets.

Connected below

Pyrocosm leads on to Spellfire Salvo.

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  Spellfire Salvo

  Arcane Salvo can stack 5 additional times. Meteorite damage increased by 15%.

Same row

Also on this row: Merely a Setback or Time Twist, Codex of the Sunstriders and Lessons in Debilitation or Explosive Potential.

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  Merely a Setback

  The bonuses provided by your Barrier spells persist at 100% effectiveness for an additional 8 sec after your Barrier is removed.

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  Time Twist

  Alter Time's cooldown is reduced by 10 sec.

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  Codex of the Sunstriders

  When your Arcane Phoenix is summoned, it consumes all your Spellfire Spheres. Each Sphere consumed increases your spell damage during Arcane Surge by 1% and causes your Arcane Phoenix to cast an exceptional Arcane or Fire spell over its duration.

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  Lessons in Debilitation

  Your Arcane Phoenix has picked up a few tricks, and will Spellsteal when it is summoned and when it expires.

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  Explosive Potential

  After casting Arcane Surge, your next Shimmer will cause a Blast Wave at your previous location, dealing (54.3% of Spell Power) Fire damage, knocking enemies back 8 yds, and slowing them by 70% for 6 sec.