Spiked armor = does 1-5% of damage per attack based on opponents current remaining hp. With a full set you can deal 5 to 25% damage per opponent attack.
Example: opponent has 5000hp, he attacks you, the armor would immediately do 5 to 25% of damage to his remaining hp so if he has 5000hp. It's 500 reverb damage. If he's down to 1000 it goes to 100 (based on 10% reverb damage). The design is to never kill, but to make sure your opponents kill you quickly vs all 25 rounds.
It would also create competition between tanks and glass cannons