I realize you're probably not an ESL speaker, but try to clean up the grammar.
Is it because devour is an ability and not a spell? are there two different rule sets for abilities and dispels I am missing. It seems to me that if a healer can dispel it without missing, shouldn't a felhunter.
If you askin bout using felhunter on Council I could tell you for sure - YES, it's possible to dispell Fusion Punch with your pet. You have to devour it from Steelbreaker's tank right after Steelbreaker casts it. In our guild I always dispell it with my pet (affli PvE spec) if tank isn't paladin (otherwise paladin have to dispell it himself).
You could write a macro
/cast [target=tank] Devour Magic
where 'tank' is nick of player tanking Steelbreaker
BUT if you r gonna make 'I choose you, Steelbreaker' you have to change this macro for something like that
/cast [target=focus] Devour Magic
Right before pool you have to /focus 1st tank; when 2nd tank taunts Steelbreaker, you have to /focus him. It's pretty easy and comfortable macro for me.
I heard bout variant with using
/cast [target=targettarget] Devour Magic
In this case all you have to do after Runemaster and Brundir died is to have Steelbreaker as your target - I don't think it's hard. But I don't use it because 1) you have to use 2 macro or targetting steelbreaker when he uses Fusion Punch; 2) sometimes Steelbreaker changes target (he casts something I don't remember exactly).
1. After pool target Steelbreaker and order Felhunter to attack him - Felhunter have to be near tank, otherwise you will see caption 'Out of range' and fail to dispell punch right in time.
2. Don't forget about your Curse of Tongues - cast it on Brundir every 30 seconds. It will slow his lighting (2.0 -> 2.6 sec); you can imagine how more mana you could save for your healers.
3. Start to spam macro when Steelbreaker starts cast - in ideal you have to prevent his spell make even single tick.