How will yeast react different in 12% as opposed to 3% ABV ?
The answer i'm looking for , Will yeast get lethargic , slow down/get its a$$ kicked by the high ABV .
There are some new high yeast strains out in the market that will easily handle up to 12-15% ABV.
you will probably have to use a wine yeast to get that high of alcohol % lalvin EC-1118
White labs just came out with a san diego yeast, I really don't know much about it.