Secondly, use RuneScape 2107 gold higher-defence armour till you become good at Prayer switching at TDS, then switch to Void. How would you're good at prayer changing? If they're attacking with melee and they roar then you have to guess involving range or mage. If your guess is right then it's fine but when it is wrong then you're probably going to require damage before you switch again...

Correct me if I am wrong... it's exactly what I read on manuals I never moved to there or even completed the quest nonetheless. That's how I do it. So it's a blueprint and they do not just switch their strikes randomly, right? Nah it's arbitrary, it's just they don't really hit with melee in any way, therefore it is better to pray agaisnt magic or variety. If they are about to start ranging, when they roar, a little bone shard item will seem, and move upward, though it can be a little tricky to spot occasionally. Keep an eye out if the demon's just been meleeing.

At slayer tower you'd kill them quicker with melee so if that's what you want go with that route. Armor should be your best magic defense (Attack is melee but it's defense relies off magic d'hide and the like) or if you really feel like praying (Bit of a waste unless you're fighting the mutated ones using a cannon) then best prayer protection and plead protect melee. For weapons go with your greatest slash weapon.

However I personally would do range because they are quite amazing for range xp being basically giant meatsacks. Furthermore, there are lots of semi-safespots throughout the slayer tower to range them from. As you'd be attempting to safespot them (Getting them caught on walls, piles of rubble and such as they take OSRS Gold For Sale two squares) go to your very best range bonus equipment, archer helm/robin, finest dragonhide, snakeskin boots/ranger.