Alrighty then. By the way, soloing in guild battles is a hard thing to do, works better if you have agood build helpful lto the team
Now, since you want some healing, your fire wont be the best it can be since you have to split up the attributes.
Orison of Healing
Heal other
Heal Party
Immolate
Phoenix
Ridgorts Invocation
FireBall
Glyph of Energy
Fire 12 (10 plus minor rune and crown thingy)
Energy Storage 11-12 (minor rune there)
Healing 10-12
This is just a rough build, But orison of healing is a good healing spell with fast recharge. Heal other is more expensive but heals more. And you said you wanted heal party.
Now, for fire: Immolate causes damage and then starts them on fire. All around good spell.
Phoenix is a good area of effect, and also sends a fireball at target enemy with does additional damage. A firball and inferno mixed into one

Fireball s a strong fire spell, throws a fireball, what mroe is there to say.
Ridgorts Invocation is expensive, but major damage! Does damage to everyone in an area then sets them on fire.
Glyph of energy will help the cost of ridgorts, and anything else.
This build hopefully has what you want. I know you say you like to play solo, so i tried to get a variety of skills in there to keep you alive while doing some damaage, and also healing your teammates.