Blizzard’s September 24 beta update changes the Mage in four lines: an Arcane Missiles line-of-sight fix and three Fire changes.
Arcane Missiles now checks line of sight once, at the start of the channel, so a target that steps out of sight mid-channel no longer stops the missiles (September 24 development notes). Fire gets longer windows: the 
Wake of Fire buff lasts 30 seconds (was 20), which Blizzard’s note ties to the mana breaks between fights while leveling, and 
Hot Streak lasts 20 seconds (was 15). 
Ignite no longer double dips on percentage damage increase modifiers. When this post was written, our spell pages and the Mage talent trees were on build 1.60.1.69913, and Hot Streak still showed its 15 second duration there.
What to do: if you play Fire, the longer Wake of Fire and Hot Streak buffs are in the beta now; check the durations on your buff bar. Arcane players can keep channeling Arcane Missiles at a target that moves out of sight after the channel starts.
The changes at a glance
- Arcane Missiles: line of sight is checked once, at the start of the channel, not per missile.
- Wake of Fire (Fire): buff duration 30 seconds (was 20).
- Hot Streak (Fire): buff duration 20 seconds (was 15).
- Ignite (Fire): no longer double dips on percentage damage increase modifiers.
Related on this site
- Mage talents
- Mage
- Arcane Missiles (spell)
- Wake of Fire (talent)
- Hot Streak (talent)
- Ignite (talent)
