You are correct, nothing prevents you from mixing rage and ferocity. I have never seen anyone try, mind you, and I don’t know that many DMs would go for it, but you are reading the rules as written correctly.

Note that if you get this strict, you may have problems then using Extra Rage to get more ferocity. The feat doesn’t mention any such possibility (obviously, since it was published first), and ferocity itself doesn’t either.

Ultimately, ferocity is a variant from a web article—a relatively well-done one, but still. It doesn’t cover everything. Your DM has to make decisions like this about how to handle corner cases like this. And that decision should be more based on what is good for the game than based on what the rules say it what anyone suspects the authors intended. Is rage+ferocity too powerful? I don’t know; that is a huge chunk of Strength, but you will be badly limited per day so maybe that is OK. But maybe not; that is a huge chunk of Strength.

You are correct, nothing prevents you from mixing rage and ferocity. I have never seen anyone try, mind you, and I don’t know that many DMs would go for it, but you are reading the rules as written correctly.

Note that if you get this strict, you may have problems then using Extra Rage to get more ferocity. The feat doesn’t mention any such possibility (obviously, since it was published first), and ferocity itself doesn’t either.

Ultimately, ferocity is a variant from a web article—a relatively well-done one, but still. It doesn’t cover everything. Your DM has to make decisions like this about how to handle corner cases like this. And that decision should be more based on what is good for the game than based on what the rules say or what anyone suspects the authors intended. Is rage+ferocity too powerful? I don’t know; that is a huge chunk of Strength, but you will be badly limited per day so maybe that is OK. But maybe not; that is a huge chunk of Strength.