User blog comment:Necrorider/Issen, the Cruor Swordsman/@comment-5800449-20130313155958/@comment-5800449-20130313161355

"Renekton's abilities have no cost related to them and their use is limited only by cooldowns. Instead, he uses Fury as his secondary resource. Renekton starts with 0 Fury and it is capped at 100. Renekton gains 5 Fury with each auto-attack, and with the use of some of his abilities. When Renekton has 50 or more Fury, his next ability will consume 50 Fury for an enhanced effect. Fury will decay at a rate of 5 per 2 seconds if Renekton has not dealt or received damage in the last 12 seconds."