AST mana problems.

[DeadRiser]

I almost ALWAYS save or use the spear card for myself.

The ability cooldown reduction affects all abilities, including Luminiferous Aether (refresh).

Also, try using the ewer on yourself as well. At level 60, it reduces the potencies by a lot, especially Helios and Aspected Helios.

If you are having problems, try casting Aspected Benefic and Helios on the tank and cast Time Dilation on them. Both regens last for 30 seconds and that requires less healing.
If a lot of AoE is going out, don't be afraid to cast Synastry on the tank either. So instead of using Helios, you can use Benefic on other party members and those heals affect the tank as well.

I had that problem in the Vault, but now that I understand all these little things, life is easier. Also make sure you are geared correctly, especially your weapon.