Basically, you don’t want Tibarn to be adjacent to his allies.
His prf weapon has a Slaying Effect, so Galeforce, which is normally a 5CD special, turns into a 4CD Special. When he’s not adjacent to his allies (so similar to Solo skills) he gains +5 attack and gives the enemy -5 attack, and he gets forced doubles.
Then there’s the whole “adjacent to beast/dragons, or not adjacent, transform” effect, but other than that his prf weapon is pretty simple. Stay away from people, essentially, lol.
His B skill, Dive Bomb, grants a Desperation effect if both him and the enemy are at, or above, 80% HP. So he can go in, double an enemy, and proc Galeforce before the enemy can counterattack.
For seals, you can do Death Blow 3 (although this gives him a lot of attack and you have to worry about one shotting which is a problem when trying to proc Galeforce), or… Well, anything really.