To add to this:
Elden Beast is even MORE bullshit than what I described. The sparkly orbs have such a high duration, that in the meantime he can cast such a combination of techniques that there is no chance to get out there alive (at least I don‘t see any). The most problematic one was: Sparkly orbs, shooting stars and basically any other attack. You literally can‘t have enough stamina to outrun or dodge all of this and at the latest when you are out of stamina it‘s game over. Especially painful is this combination, because for the shooting stars you need to run in one direction, optimally when you disabled lock-on. That way you lose your orientation where the beast is (that your whole screen lights up in yellow sparkles doesn‘t help too), so even if you make it out of the shooting stars, the moment when you found the beast again it is already too late.
Oh and do you know that it also has a grep attack? Me neither, until it killed me with it twice.
However there is a happy end to this: after roughly an eternity (and so many tries that Radagon was reduced to a mere inconvenience) I was finally able to beat it. But this was all due to RNGesus. This fight must be one of the worst designed boss fights From came up with, if you just rely on melee without any kind of support (summons, ghosts).
Not sure if I will go up against Malenia. Saw her second phase once, but the first phase is so tedious, due to how long you sometimes have to wait for openings and her self-heal.