PB&LotJ is a strategy (or sub-strategy, depending) that involves at least two Vivosaurs. One knows the skill Law of the Jungle, while the other has the ability Parting Blow. At some point in the match, usually about halfway through, the player has the Law of the Jungle Vivosaur let loose and chow down on the Parting Blow-er, leaving it with 1 LP and triggering the ability. The LotJ user now has some extra LP to play around with, and the recipient Vivosaur now has a significant attack and accuracy boost, and can proceed to dish out some serious damage to the other team.
Note that Law always goes for the Vivosaur with the highest LP, so if the target wouldn't be your PB-er, DON'T USE THE SKILL.
Also note that this strategy is MUCH easier to perform in FFC than in FF. The reason for this is LotJ costs 150 less FP in the former, and the max FP recharge is also fifty points higher.