Master Sura is the final boss, appearing after completing 3 main stages and thier bosses. Considering that in this game it is easy to get hit, but much harder to regain healt easiest method is to focus on health regenerating items, i often start with item than regerates health on critical hit. Items increasing chance of getting health orb or healing after killing an enemy are nice too. Other than that i tried to get as many damage and critical strike chance increasing items as i could (more crits = more damage and health), and used purple hood (increasing evade and crit chance).
Keep in mind that, this is only a suggestion, and does not guarantee win. Sura is a hard and chaotic boss. And you will mostly need skill and expierience with the game. So good luck fellow wizards.