I feel like Hydra is setup at a level that isn't for the level that it is released to players in game, but they just put a level on it and then said alright this is good enough.
Hydra unlocks at level 45. Doom tower unlocks at lvl 40. Live Arena unlocks at 50.
Doom Tower Normal ranges of mobs from Lvl 75 to lvl 225.
Live Arena doesn't start till 5 levels later so you can't start building the Area Bonuses for it till then.
Clan Boss even starts with an "Easy". Brutal is level 150 can't recall the other levels off top of my head only found a picture of Brutal CB that showed its level.
Hydra the lowest is Normal and the starting levels of all 4 bosses are 260. 260 is just above Hard Doom Tower Floor 50. I could see Normal being set at 180 or 200 for each boss for Normal and then going up by like 40 for each higher tier.
There are people in my clan that I see looking at their clash stuff that have used 3 keys and don't even have the 1st chest in Normal and they are in the high-70's mid-80's. Imagine having a feature that unlocks for all players to participate in at level 45, but that game mode you can't touch for months or years.
There was a long time that I never touched Hydra or attempted it since when it unlocked at 45 for me and I first entered it no matter that team I put in it my entire team was killed before I even got a turn. I didn't start working on it again till Hydra Clash came out since I had read the chest rewards as Clan Point wise instead of personal. 35M for a single chest puts it out of the reaches of mostly all except for those with certain teams of champions or have already played for many many years. You can reach level 45 in about a month and a half or even faster in game.
To be able to get to 35M points you need to be able to almost 1 key Hard which is 4 bosses of level 280. Since 18M points is 35M Clash points in Hard in a single key. If you can't 1 Key it then say you do 10M you get 20M points then you have to do another 15M of Raw 1x Points damage in either Normal or Hard with no multipliers. Since only the first key gives a multiplier. None of the level 100's in the clan I am in get even close to 35M they are all in the low 20M's.
The 35M points was probably setup by play testing using only level 100 players that had NM, Brutal, and Hard unlocked. Probably the vast majority of clans (since there are a ton of clans) don't have anything but Normal and Hard unlocked.
If you take the costs of the Clash chests based only on clans with all difficulty levels unlocked 35M isn't nearly as hard. NM put up Unkillable and then get a provoke and AOE burn out you will do 4M. Well NM is 4x multiplier you just got 16M points for only surviving 2-3 turns till the Unkillable wore off but the burns got ya the points. Do the same in Brutal get another 3M now you are at 25M. Go and actually battle in Hard and get the first chest in that at 6M you're now at 37M. If you place you get the Clash chest. It is easy to setup teams for a quick burn. Like for hard I have tested it out with some teams I can just use some high speed that put up unkillable and let HP Burn do all the damage from the ticks and that gives me a couple mil in Hard. Doesn't do much in normal though since their HPs aren't that high.