Because you must fight both Grotesque Guardians at once, it’s necessary to use both melee and ranged to take advantage of their respective weaknesses.

Phase 1

Start off the fight using the protect from missiles prayer and use range to attack Dawn down to 55% health.

Phase 2

You should now switch to using the protect from melee prayer and start attacking Dusk with melee. Upon landing the first blow, you should immediately retreat at least 3 squares to avoid his AoE explosive attack. You can now continue to attack Dusk while avoiding the falling debris until Dusk also reaches 55% health.

Phase 3

You will now be under attack from both Dusk and Dawn at once. Switch back to your range gear and use the protection from missiles prayer whilst attacking Dusk. She will occasionally fire out three healing orbs, which you must click on and absorb the energy from these orbs as soon as possible in order to avoid Dawn absorbing health from these orbs. You must now finish off Dawn with your Rockhammer.

Phase 4

Once Dawn is dead you can now switch to your melee gear and use the protect from melee prayer. Focus now on finishing off Dusk. He will occasionally use a special attack where he teleports the player inside a 3 x 3 square surrounded by fire. You must escape this square through the open gap in the wall before you are hit and take massive damage. Finish off Dusk with your Rockhammer and you’re done.