Board Thread:Questions and Answers/@comment-32856983-20180315152656/@comment-33532122-20180315175341

The link is very easy to understand.

Permanent = forever = for life

It's just for H2H and just in opponent turn. Example:

You have been challenged, responded the 2nd and 4th rounds. However, your last fighter have a defensive perk, when your opponent fight this last fighter, the perk will be active.