How did Xykon survive his fight...

[Forikroder]

Let's say Xykon's level 21. Average hit points would be around 142. Remember that Sunburst allows a save for half damage, so if he made it he'd be taking 52 instead of 105, leaving him at 90.

Then the Crushing Hand deals 2d6+12. Average is 25, leaving Xykon with 65.

10d6 averages out to 35, leaving Xykon with 30 after the Superb Dispelling.

And, last and least, Explosive Runes does 6d6 damage. The average here is 21. Xykon gets through that with 9 hit points left.

On average, if Xykon makes that first save, he survives.

http://www.giantitp.com/comics/oots0653.html

the explosive runes was more like a light breeze to him it was flashy but only managed to knowck away the Phylactery