As a bonus, Copy: Opp Ability has too many flaws to work.
1. Balancing a card's stats and ability would be insanely difficult with that bonus.
2. Some card's abilities are useless against themselves. Try using Spiaghi's DR against him or Tobbie's PR.
3. Some cards don't have abilities or have abilities like Backlash.
4. Courage, Confidence, and Revenge will only be usable by the opponent; unless they play really badly, you're not going to copy those on the right turn.
5. Stop would be impossible to copy, barring strange card design. As far as I'm aware, only using CoA as an Ability against
Mini Mund has even a chance of working.
6. Protection would be useless in the vast majority of situations.
7. If you're not playing Mono, Support is less effective.
8. Leaders can't be copied, probably. I base this assumption on their immunity to SoA and their functions.
9. Some abilities (like
Bodenpower) are weak to work with a strong bonus or stats.
10.
Nightmare and
Piranas enviable abilities are protected by their bonus.
CoA would be an interesting Ability, but as a Bonus, it's just too random and weak. It would be a struggle to use, fight, or balance cards that are that opponent-dependant.
CoB would be easier on all fronts. It would create mirror-matches that weren't exactly "mirrors" and could be balanced similarly to
Piranas and
Nightmare (strongest against bonus-reliant clans).
Heal 2, Max 10 sounds fair to me. It would function similar to
Freaks.