Commented in here a couple times and have been keeping tabs on the thread. I believe the ideal solution is to move mages to a Cleave model for spreading DoT's and that said DoT's are all applied as a function of casting our direct damage spells.
Blue Skying all Bombs would be;
- single (via cool down on spell) target instant cast
- chance to proc spec specific spell (all bombs work for all specs)
- put a DoT on target
- apply an effect (unique to bomb being used)
Then give all specs a "cleave" spell, with an appropriate cool down, that they use to push DoT's out to either closest X mobs or all mobs within X radius (opportunity for a glyph).
Each bomb could be unique in how it procs, effect it applies, duration and strength of DoT applied.
If as I suspect with 6.0, they move mages to having a resource (think holy power, runes, combo points, etc), bombs could also interact with resource generation or have their strength improved via using resource. As an aside, I believe they will go to resource system which will enable them to eliminate existing 90 talents.