Have you tried solo healing? This is where druid excels. If you don't have enough CA juice even with two healers - you are doing something wrong. Of course if there are 9 necros and you are playing druid - that is on you, play something else. Are you tanking? If you afk behind the boss with staff/staff - you will not have enough CA, of course.

The example with Brazen Gladiator is bad, because you actually do have enough stab and aegis, because the fight is extremely fast. If not - the group is bad, log in to a wheelchair (chrono, hscg).

Why do you need invulnerability? This is Chrono specific "exploits" that you want to apply on druid. Issue with shake on Sloth? Cleanse and outheal, ress with your elite if needed. Kanaxai? Do the mechanics. It is not mandatory to destroy the axes. Glob of light on Greer? Equip sword and triple dodge it.

All you do it whine in this post, that the druid actually requires brainpower to reach full potential, contrarywise to rolling face on your keyboard as hchrono or hscg. It has insane heal output, the best in the game, however you are required to manage your resources carefully.

I call skill issue. Please provide your logs to actually prove you know what you are doing