Bosses
Bosses drop good loot that will definetly be helpful
Bosses are enemies that are much harder. They are usually at the end of the dungeon and there are minibosses in the middle of the dungeon. A boss will usually give you an important item. Here are some items thats bosses will give you.
I'll give you help on an easier boss in TOTK. Colgera is so easy. You can either shoot at the ice parts or dive through it. Don't worry about fall damage while going through the ice it won't count.
Another is Marble Gohma. He is a little harder but not by much. He is just a stone talus on steriods. You just have to ascend through him and hit his eye.
One more thing. The hardest boss in my opinion was mucktorok. He jumps though the mud and is hard to hit. You are supposed to use sidons water ability but arrow also work.
Last and definetly the hardest out of any of them. Ganon. I'm not going to spoil to much but he has three fazes and three different weapons. He also brings in extra troops. That's all I'm going to say but be prepared.