Idea behind the build.

You can get fire spell power higher than any other choice. With Cleric domain Fire, you can max out the fire spell power and do damage with fire and light spells.
This build is for Low reaper (1 or 2, can go higher but you end up healing more than DPSing). Problem with higher reaper is that DPS does not scale well.
There are two versions. One with Max DPS going 15 cleric/5 FS, and another going 17Cleric and 3 FS with 17th cleric level giving you Implosion(one of the best spells in the game)
My preference is with Implosion since it gives you more options in reaper.

Strength
Your DPS vs Undead and cold creatures are awesome. At level 30 you can get 1000 spell power (not counting max, empower and stuff).
You have many AOE spells that does lots of damage, (they are mostly fire though)
You can self heal well and decent PRR can be achieved.
Spell points are not really an issue in High levels.

Weakness
At low levels you are running out of spell points. (had to carry around a hireling for DV)
People expect heals from you.


I went Human(for the extra feat) 1-17 Cleric and 18-20 FS

Str 10 (2)
Dex 8+
Con 16 (10)
Int 12 (4)
Wis 18 (16)
Cha 12 (4)

I used skill points on Heal, Spellcraft, UMD, and Concentration. When I got more from Int Tome, I used it for Jump

Feats
1. Maximize and Empower
2: Fire Domain
3. Completionist (if I did not have this choice, I would have taken mental toughness)
5. Scorching Ray
6. Quicken
9. Heighten, Fire Wall
12. Enlarge
14. Firestorm
15. Evocation
18. Wizard Pass life (or Improved Mental Toughness)
21. WellSpring of Power
24. master of light
26. Fire Spell Power
27. I took Intensify, but you might consider Ruin
28. Frog
29. Arcane Pulse
30. Glacial Wrath or Greater Ruin, Scion of Fire

Enhancement

Human- spell power boost and Wis 3pts

Warpriest - 3 core (15 fire spell power) Toughness III, Sacred Touch II, Wall of Steel III, Wis 13pts

Divine Disciple 6 core (go light), Universal SP III, Universal SC x 4, Fire SP III, Quicken III, Searing light III, Wis x 2, Holy Smite III, Flame Strike III, Evo x 2, Divine Empowerment 45pts

AoV Font of Power, Scourge III, Smiting x 3, Just reward III, Wis 15pts

4pts for whatever you like. I went with Improved recovery and Spellpoints

* I used Nimbus of Light SLA at low levels but changed it out once I got the higher levels (12) , I kept Holy Smite for Blinding ability even though it does very little damage.

Exalted Angel Epic Destiny
Twists: Empyrean Magic, Flames of Purity, Fire Dragon, Cocoon (just in case you get Quelled)

Play Style.

Put all the Meta on the SLAs, but not on Sun beam and Sun bolt. I use the 4 long range spells (Scorching ray, Searing light (just the SLA), Sun Beam, and Sun Bolt) at range. Use SLA Firestorm and Flamestrike on crowds. In Epic one of the best SLA is Divine Wrath. Use Implosion whenever it is available and there are more than 3 targets. Divine Punishment is used only on bosses without any meta. With 60+% crit chance and SLAs, you rarely run out of spell points. I always have quicken on. I want Energy burst twist, but I could not find a way to afford the cost. Targeting firestorm can be tricky. You cannot target a mob. but an area. There is also a delay before effect takes place. sound burst and comet fall are useful for CC.

Few thing you really want for equipment.

Legendary Shroud Fire SP weapon... need only smalls and mediums to make. Heroic and Legendary Orb from the Newcomer. Fire Trinket from RSO Raid. Upgraded Lantern ring.