
Black Panther is an ally that is either too expensive, or suffers too much consequential damage: 4 ER (5 minus 1, the Event you tutor from the discard pile) for either 2 damage and a chump block, or 4 damage, is just a horrible ratio.
The only cost-effective use I can see for this ally is to play him with Sneak Attack, use his ability to tutor either a Go Down Swinging or a Save the Day card from your discard pile, make Black Panther attack or thwart, then use the very same card you've attached to him to discard Black Panther to deal 4 damage (with Go Down Swinging) or remove 4 threat (with Save the Day), since he would've been discarded anyway with Sneak Attack. Damage-wise, such a combo would deal 6 damage (2 for Black Panther's ATK, 4 for Go Down Swinging) for 3 ER (1 ER for himself, 2 ER for Sneak Attack; we do not count Go Down Swinging since it's tutored from your discard pile, as explained above). 2 damage for 1 ER is good, but it's a very clunky combo which requires your deck to be built around it, with lots of cards required just at the right time or in the right place... and you're also wasting a block. Just not worth it.
I simply house-rule him with 1 less consequential damage for both ATK and THW. Otherwise, I don't see any reason to include Black Panther in any of your decks, especially with so many better options out there (especially in Leadership).