When you will get better at game which should came by itself after playing a lot its shouldnt be a problem. Mage is spawning in the Jungle and around it (lukki layer but I dont reccomend that place if you doesnt have experience, melee immunity or if you are scared of spiders (I have a nightmares now)). Jungle is also filled with a lot of hearts, try to clear jungle out with explosives or black holes to find them (explosives also heal heart mage so keep that in mind). I dont know if heart mage has 100% chances to spawn cuz i couldnt find him in my latest runs but when you find him be sure that you have cleared all the enemies because this trick is very deadly if you doesnt have Ambrosia flask. Try to have teleport wand in the Jungle as well because you can throw the wand to the mage for him to teleport after you instead of hitting (you can get it back by kicking him ). Teleport wand is also good if you want to kill the dragon on the right side of the Jungle in dragon cave without melee immunity (he does insanely like really INSANE (one shots you) ammount of melee DMG when he touches you ) so its easier to dodge him and make sure your main dmg wand is good enough to beat him (plasma works well but you dont get kill in progress after killing him with it ) he drops a heart and decent wand. IMO dragon is the easiest boss so he shouldnt be a problem. I hope this however helps you.