The full build looks like this:
In case the link doesn't work (or if you are lazy

Ineptitude {E}
Phantom Pain
Conjure Phantasm
Bonetti's Defense
Ether Feast
Healing Signet
Physical Resistance
"Watch Yourself!"
16 illusion magic
10 inspiration magic
7 fast casting
7 tactics
Vokur's Cane
Jeweled Chalice (craft at the droknar's forge weapons merchant)
Full rogue's armor
Now, the first thing you need to realize is that devourers can eat you alive if you are fighting something else. Should ether feast get interrupted, you will be lucky to finish the fight with your life. You can, however, fight two devourers at the same time safely (I have not tried three, but you may be able to do that as well)
Assuming nothing horrible happens and you take your time (remember: devourers are hidden until you get close. Don't just run in and aggro something, check for them first.) You can kill the minotaurs with a fair amount of ease. I have succesfully killed groups of up to three of these at one time.
The griffons themselves are not so easy. With both your armor boosting skills up, you should take about 9-11 from a normal hit, and approximately 18 on a critical. The difference between griffons and minotaurs however is that griffons get berserker stance. This will noticeably increase the damage you are taking, and so makes griffons harder, as does the lucky dual final thrust hits while you are below 50% health (they did 100 each, try to avoid this if you can but it is all luck in the end)
Currently, there seems to be a glitch that causes one of the griffons in a linked group of griffons to not attack until you kill one (so, in a group of three you will fight two, then two, then one, and in a group of four you will fight three, then three, then two, then one) This is good, since I have only once gotten the build to survive three griffons at one time, and I think that may have had a good deal of luck with when they hit with final thrust.
Griffons also appear to have two kinds of spawns. In one case, most of the groups come in packs of three, and are relatively easy to handle. In the other case, a good portion of the packs come in groups of four. I'll post up more info if I find anything else out about griffon spawns.
Execution on minotaurs:
Check the immediate area for devourers, use physical resistance, then wand one of the minos. Once you have aggro, use conjure phantasm, phantom pain, and ineptitude. Begin wanding the minotaur that you cast all the spells on (deep wound does not seem to get applied when it first gets placed on a target, you need another hit. I believe this has been discussed in other places as well) Use "watch yourself!" when it is charged, try to keep it up as much as possible. When you have taken a bit of damage, use ether feast. Now you will be in a few different situations. In the first case, your hp will be fine, and you can continue wanding the minotaur and using ether feast until he is dead/almost dead. In the second, you will have taken to much damage to continue with your attacks (or you are low on energy). If this is the case, hit bonetti's defense. Once ether feast is charged or almost charged, start casting healing signet. Right as HS finishes, use physical resistance and, if it is charged, "watch yourself!". Then follow with ether feast, and you should have healed up about 200 hp, give or take a little. If your target is not yet dead and he has no more degen, hit him with another conjure phantasm and continue wanding him. Once he goes down, move to the next minotaur and repeat.
Execution on griffons is almost exactly the same, but you need to make sure that your target is one of the griffons attacking you rather than the one standing off idioticly while you slaughter his buddies, as the blind from ineptitude takes off some of the pressure and gives you time to heal. By the way, bonetti's defense will not give you energy if the miss is caused by the blind rather than from bonetti's. It is therefore best to use bonetti's while the enemies are not blinded. Doing this will also give ineptitude time to recharge (though not fully) and helps to, like ineptitude, take some pressure off you for a moment.
As I have said above, you can get more efficient farming using other builds, but if you ever find yourself bored of pushing the same skills hour after hour, at least you now have a fallback.
-Banebow