This is a long fight. Slade fights you for awhile, then flees and lets his henchmen attack you. You must defeat all henchmen before he will come out of his barrier. Slade has demonic powers received from Trigon. It is better if you to keep your distance from him. When he uses his charged attack, it will cause serious damage to anyone up close, hitting them three or four times. He will attack you three or four times before you can finish him off with your team attack.