Regarding playing a level 50 cleric:

Symbol buffs:
Pinzam gem is a jasper (cost about 8gp or so depending on faction)
Naltron gem is a peridot (cost about 11pp or so depending on faction)

Tanks NEED the extra HP's that Naltron brings for dragon runs, etc. If you
cannot afford the gems, have them give you pp for them or bring some in
advance. (I Naltron everyone for dragons, but that is just me)

Regarding Reso and AOF:
In extreme combat situation I will Shield of Words all the tanks
(+AC/+defense) and AOF the casters. If a 49+ druid is around and they don't
mind, they can cast Skin Like Nature (SLN) on tanks (does not stack with
reso and reso and SLN will not over-write each other) You will still need
to cast your AC buff (SoW or AOF). Druids can also help to cast the Endure
cold/fire buffs.

Regarding Complete Heal:
I don't use in dragon situations. Occasionally I use on the planes, dungeon
hunts and fire giant type runs, but ONLY on tanks with HP's over 2500 or so.
Mana cost for C-Heal is 400 (versus 250 for Superior heal) and can save you
a bit of mana on high health point tank types. If you do use it, it is best
if you start to cast when HP's drop to 2 bubbles. You will get a feel for
when you will have time to do this and when a superior heal is needed for
the lower casting time.

~Sirensa
Solusek Ro