Mage

Major

• Glyph of FireballLevel 15A faster Fireball for standard Fire; the lost damage over time matters little.
• Glyph of Living BombLevel 60Living Bomb's periodic damage can be critical: a big gain against one or several targets.
• Glyph of Molten ArmorLevel 62More critical strikes for all three specializations: the glyph shared by the three trees.

Minor

• Glyph of Blast WaveLevel 70Blast Wave costs less mana and no longer knocks monsters back: your tanks will thank you.
• Glyph of Arcane IntellectLevel 15Arcane Intellect and Arcane Brilliance cost half as much mana.
• Glyph of Slow FallLevel 15No more feathers to carry for Slow Fall.

Other choices

• Glyph of FrostfireLevel 75Instead of Glyph of Fireball if you play Frostfire, with Frostfire Bolt as your main spell.