E3M8: D'Sparil's Keep (Heretic)

E3M8: D'Sparil's Keep is the eighth level in The Dome of D'Sparil episode of Heretic.

Walkthrough
You start in a water area, with various Gargoyles around you. In the corners of the pool, there is an Ethereal Crossbow, some Ethereal Arrows, a Shadowsphere, Wings of Wrath and a Silver Shield; collect them if you need them, then fly to the higher area, collect the pair of Lesser Runes, and you should notice a wall slightly different from the others, that isn't scrolling. Open it; the secret behind contains a Tome of Power, a Bag of Holding, a Quartz Flask and a Chaos Device. Now enter the opened portal. You will land in a small room with a pair of Disciples of D'Sparil, and cover. Blast them and pick the Dragon Claw and the Energy Orb, as well as two Crystal Vials and any Claw Orbs the Disciples may drop. Now go back through the portal. Enter the newly opened one in the main room, but make sure to activate your Shadowsphere before. You'll land in a room filled with Nitrogolems. Among them there are Gauntlets of the Necromancer, Ethereal Arrows and a Claw Orb. Use either the Dragon Claw or the Gauntlets to get rid of them. Now go back to the main room and enter the third portal. Three Ophidians will greet you. Destroy them and grab the pair of Lesser Runes, and activate both switches. An Iron Lich will be your new obstacle. Behind him, the Hellstaff, Crystal Vials and Greater Runes, as well as the portal. Suggestion: activate your Tome of Power and blast the Lich with the powered Crossbow. This should finish him before he has time to deal any significant damage. Back to the main room, enter the last portal. You'll land on a trident-shaped ledge, with a Tome of Power, an Enchanted Shield and a Phoenix Rod. You'll notice D'Sparil and his Green Chaos Serpent, but don't worry about him yet. First off, run all around the large arena, collecting everything you can, including the Wings of Wrath. Fly to the ledge above, there are plenty of Mace Spheres, as well as two secret doors, one on the far end of each side, containing a Mystic Urn and a Ring of Invincibility; at this point D'Sparil should rarely if ever even attack you until you start fighting him in earnest. Now pay attention to D'Sparil. Use the Phoenix Rod from a distance and you should be safe, but be aware that the Serpent will start to run and fire more fireballs the weaker it gets (by this point in the game, you should have no trouble circle strafing). When D'Sparil rises, his only attack is a fast lightning bolt that deals massive damage but gives you plenty of warning, but the real challenge comes from his teleporting around and summoning Disciples; you should eliminate him as quickly as possible since the Disciples he summons may annoy (or kill) you. The Hellstaff might be an option to kill him, but consider the Phoenix Rod as well - D'Sparil teleports rather often so slower projectiles from too far away and continuous attacks won't work so well. If you've got a Firemace, it won't be so hard for you, and if the Disciples he summons get out of hand, consider using a Tome of Power with the Dragon Claw to clear them out. Good luck. When the Serpent Rider dies, a passage with a switch will open at the far end of the arena. Then, stairs will rise to the exit portal. Congratulations, and enjoy the ending.