Adrenalin is an attackers set, it provides a boost to the REG of all attack type creatures.
Adrenalin I - Attackers: +2 REG
Adrenalin II - Attackers: +4 REG
Adrenalin III - Attackers: +6 REG
Adrenalin IV - Attackers: +8 REG
Adrenalin V - Attackers: +10 REG