the game itself tells you the changes. reffer to that
Bossses dont level up, you're prob confusingvisaul effects
for the first boss, get a decent ranged skill and a sword with good elemental damage, you can take out the crystals before he reaches you first this way
instead of health potions get focus potions instead, he doesnt deal that much damage so you dont need to waste inventory space with alot of health potions when a focus potion can be used for a 10 turn effect
Dont just randomly throw swords at it, sword throwing is when you're in a pinch and low on health, if after stunning the boss you're low on health, use a mobility skill tomake distance, then either use a ranged skill or throw 1 unimportant sword,but always keep and use your good ones until 1 durability