in the game a 'buff' is an enhancement that lasts for a certain number of rounds with the only exception of barriers, since they are limited to 1 per field and disappear when the ninja that create them dies.

i suggest you to read again what i wrote.

If i give an univocal definition of buffs like 'an enhancement that lasts for a certain quantity of rounds' then barriers would fall in this category. That's why i said 'with the exception of...' i thought was pretty clear.

it's exactly what i said.

lets try to reverse the question: 'do all the enhancements that last for x round are buffs?' since the answer is 'no', then naturally comes the following question: 'what is the set of the enhancements that last for x rounds that are not buffs?', answer: 'barriers'.

So, if you want to say in one single sentence what is a buff, how would you do it using those words?

answer: 'a buff is an enhancement that last for x rounds, but barriers are not buffs even if they are enhancements that last for x rounds' and how would you avoid to repeat 'enhancement that last for x rounds' since you just said it once? answer: 'a buff is an enhancement that lasts for x rounds, with the exception of barriers'.