Not really in the mood to make a full on, fancy written guide right now but I can tell you the basics based on having killed 1000+ glacors on another server (probably similar if not exactly the same on here).
I went with soulsplit and blood barrage, since I had Virtus (highest gear on said other server) and my healing just outdid the Glacor's damage. As for gear and what spell or combat style to use, it might differ here, you should ask around for that.
On to how to kill them - simple attack, best from a range (magic is probably the best on Ata as well) so that you don't have to deal with its melee damage.
If you don't think you can outheal with Aura, soulsplit and what not, you'll have to pay attention to its arms (from the Glacor's perspective):
- When it raises its left arm, it will deal magic damage, so protect from magic (deflect curses)
- When it raises its right arm, it will deal ranged damage.
- When it slams the floor, just step away from where you're standing, it will deal large damage underneath you.
When the Glacor gets to half of its health points, it will summon 3 glacytes: Unstable (red), sapping (blue ish) and enduring (again, blue ish). They each have their own effect. The Glacor will take over the effect based on the LAST glacyte you kill, the effect is also stronger on the Glacor than on the Glacytes.
- Enduring glacyte takes reduced damage, the Glacor will take quite some time to kill if you kill this glacyte last, so best not do this as last one.
- Sapping glacyte will drain your prayer points. Depending on your gear and setup, I never minded killing either this or the unstable glacyte, simply depending on which one I killed faster, it didn't really matter to me as I didn't use food.
- Unstable glacyte is some sort of time bomb. It counts down and then it will explode, dealing damage to you if you're close to it. I usually try to kill this as last one since, if you use decent gear, you will kill the Glacor (having taken over this effect) before it manages to explode in your face.
That's all there is to it I think. If you've never done them before, it will take some practise, but all in all it's quite simple.
I hope it helps, let me know if something confuses you.
EDIT: Added some colours for easier reading.