You understand that this is probably one of the easiest DT bosses out there, right? It literally lets you design the fight specifically in a way you can win.

Never heard of either of these two. Guessing they are both ultra-Krackens that enjoy humbling others with thier 

"awesomeness".

They can save it. Most everyone else is going to struggle and struggle hard. 

- Coag

Okay to clarify I was thinking having a red key in every area would not increase the keys needed to fight the big boss.

My thoughts were to put a red key in all 4 sections, in case there is a boss that a person can not beat in one area they still have the option to get 3 red keys in the other 3 areas.

This way everyone can have the option to fight the big boss, its not gatelocked by your roster.

Even with 4 red keys people might not be able to get 3 red keys but at least they have the option of which areas they fight in to get the red keys.

How is it easy when the boss makes copies of your champs, and they have everything the exact same.

To me that is one of the hardest bosses.

So if she is a boss in an area that has a red key im blocked out of it, but if all the areas have red keys I can just avoid that boss and go for the other 3 keys and still be able to fight the big boss.

I'm trying to think of ways everyone can enjoy the new content and not just those who are whales or kracken and have just about all the champs.

Why should 90% of the player base be gatelocked from any of the content?

1. while your team and the duplicates astranyx makes are identical, your team acts first which gives you an enormous advantage. you'll want to make sure the fastest champ on your team has some form of turn meter manipulation, so that rather than your champs going and their duplicates acting immediately after, you can get most or all of your team acting before the any of the duplicates get a turn. the most common method is tm manipulator into CC into a couple of nukers to wipe out the other team.
2. even assuming that you can't beat astranyx, she can't keep you from getting a red key; at least not by herself. all of the areas of sintranos (except for soulcross) have multiple different paths so you're never forced into any one specific fight. you could find your path blocked if you come across three or four different levels that you can't clear, but the only times a single level can prevent you from getting a key are the key levels themselves.
3. while the adding of a fourth key seems like an improvement on paper, it doesn't really hold up in practice. the idea falls apart because the area that doesn't already offer up a key is soulcross, which is a huge difficulty spike from the rest of sintranos. it's true that there's no real downside to adding a fourth key to the game, but the idea that someone could have enough dead levels to be stuck on either plageholme or deadrise, but be able to fight past the iron twins and sand devil (the two chokepoint fights that can't be avoided) and through the majority of soulcross with its stronger enemies and harsher champion restrictions all the way to either s15 or s22 (i doubt plarium would be generous enough to stick the key on s11) is, quite frankly, ludicrous.

I understand your first point, and it makes sence but that method doesn't always mean a victory.

Your second point while yes there are multiple paths, you reach a choke point like you just enter the area and have to beat a boss before you can progress further, and is assuming the path that leads to that area a person can beat.

Your third point makes it seem like people can't have champs that allow them to just get past specific levels to get a red key vs have champs that can beat bosses, especially since every battle is roster based.

Everything is roster based, so while someone might not have the champs to beat 1 boss, doesnt mean they don't to beat a different one. 

Like you said there is no downside to adding a 4th key, especially since it is all roster based, so like i said above where you might have champs to do things in one place, you might not in another.