The Problem about legendarys

so the problem isnt that legendarys are op ,no they’re just luck dependent.If you draw doomgate in your starting hand doomgate decks work out quite fine.if it is like the last card in your deck ,the deck has no win condition at all.same as auroras dream.although you dont need it in your staringhand you still need it pretty soon.i would like if legendarys would have to be in the first 15 cards.

I think you just misunderstand what is a legendary card. U are not supposed to make a “DOOMGATE deck”, you must build a deck based on creature and some sacrifice mechanism (for exemple) and, doomgate is there to give you ONE more win condition.
You can’t build a deck on only one card, think about aurora dream for exemple. If it s in the last 5 card of your deck, it simply near kill you if u play it after.
There is no “Tutor card” (a card who make you the possibility of draw an other card of your choice) like in Magic in this game, so You can’t build combo deck like that.

If your deck have no winning condition without a legendary, i sugest you to improve your deck with some other kill condition.