Cone AOE: The spell fans out in cone blasting everything in its path. Use shotgun choke rules for this effect
Drain mod: +2

Nexus AOE: Area effect centered around the caster, blasting everything within range, the caster is not affected.
Drain Mod: +2

Burst: The mage churns out a torrent of elemental energy towards the target - Spell functions like Burst Fire from SR4
Drain Mod: +3

What do you think? Can work?

I've used the top two of those options before, but I've actually applied negative drain mods to them since they somewhat restrict the capabilities of the spell. In the Cone AOE, you can't target the spell as effectively as you can a normal AOE since it starts at you and spreads out. If you've got friendlies in that cone, then you can't just target the guy in the back and keep said friendlies out of the AOE. Same thing with the Nexus AOE; chances are that you've got friendlies around you so that effect, while nice if you're getting jumped by a lot of unfriendlies, does actually restrict the times that you can use it compared to the normal AOE.

As for the burst effect, I wouldn't personally put it in the game. If someone wants to cast the same spell three times at the same target, they can split their die pool up to do so. I suppose, on second thought, that this could provide a way to avoid splitting the pool in return for the drain code increase. Anyway, it seems more like a Metamagic to me.