Rets and healing

[Ualaa]

I'd vote Sacred Shield too.
Alt + Right click, on any grid frame.
That target has 5x Sacred Shield on them, which stack.

Instant cast, decent absorb.
Six second re-use, so cannot instantly switch if they switch targets on you.
But still, you can reapply it fairly quickly.

It doesn't cost any resources, no mana nor holy power.
Just has the cooldown.

[Shodokan]

I'd vote Sacred Shield too.
Alt + Right click, on any grid frame.
That target has 5x Sacred Shield on them, which stack.

Instant cast, decent absorb.
Six second re-use, so cannot instantly switch if they switch targets on you.
But still, you can reapply it fairly quickly.

It doesn't cost any resources, no mana nor holy power.
Just has the cooldown.

They stack but can't all trigger simultaneously.

[Owltoid]

They stack but can't all trigger simultaneously.

What do you mean by that? I have all 4 shields active at the same time