Hiya peepz,
This is my guide for to camp at waterfiend for 1 def pures without using protection prayers.
First of all go to Otto the barbarian who gives barbarian training. Bring any bow and an oak log. Talk with him about barbarian firemaking. After he telled how you can make a fire without a tinderbox, use the log on the bow. If you did well there comes a new screen on your chatbox. Talk to Otto again (twice I think), after you did this try to jump in the whirlpool. When you havnt completed barbarian firemaking yet, you will fall and get down the waterfall.
Map of this area:
Now get armour with good range bonus attack bonus. A anti-dragon shield is recommoded because you will get 3 hits from lvl 166 dragons. If you're a little rich, bring regen bracelet which heals 2 ea minute. If you can afford it you should also replace the climbing boots for wizard boots. Ofc you can also bring ranging amulet and archer's ring (i). I'm poor atm so not wearing at the picture.... I also recomment good bolts, I use adamant. If you're 55 slayer broad-tippet bolts are great. Also don't think you should only bring 100 bolts. I mostly do 2000 bolts, and I can camp 7 hours with them. In the 7 hours i think you will gain like 250 crimsons / 40 golds / 20 greens / 10 blues.
It's not that much BUT, this is the best way for pures. (except barraging rock lobs ofc)
Here's what i bring:
After you got the armour from the bank go to the whirlpool and go down twice.
This is what cave you're in then:
Note this!! The waterfiends can attack you if your in an area of 4 spots!!
I suggest when you go for the first time to replace the range pots for sharks. You just need to learn how to lure them.
The waterfiends can only hit 11, but after you're full of drops, not out of bolts, it's good when you're high hp. This is because you can always make mistakes when a waterfiend moves after you attacked. Walk to the rocks (safespot on the map), and lure the waterfiends (3) behind the rock (See the green signs on picture). Now you've to w8 10 minutes untill they're unagressive. When they are unagressive they will walk away, so never move before they did this. When someone else in your world is killing the fiends you have no chance to get them unagressive because they will respawn next to you and attack. So look for a new world if this happens.
When they are unagressive it's just easy. Just safespot the way on the picture above.
I think this is it, maybe i change some things after.
Do you have questions about this pm me or post here.