Thought I'd post this here too so others can find it easier a walkthrough as well as Leni's great video
As for strategies, there's only one really, range and/or mage him to death, Melee is pretty pointless as he runs off and heals. It is strongly advised you use at least Adamantite arrows (poisoned rune is best IMO).
To kill him you need to firstly locate him (Typing ::rev will show you his current location, although this will only tell you his level in the wilderness, so he could be anywhere along the lateral line of that). Secondly it's best to shoot him with your bow and arrow, then run away. He will continue to follow you, lure him all the way up to red dragon isle gates, once there and on the west side of the double gates, he will not be able to attack you, leaving you free to range/mage him. If he runs off, just walk 1 square to the east (east side gate) and when he starts walking back towards you, move back to the western side of the gate and shoot again, he will then get 'stuck' there and allow you to kill him with no retaliation.
- If you get stuck fighting another NPC, he will attack you with magic, so be ready with food. - If you are in a group (no more than 3, as 3 is the maximum amount of drops available per kill) then you must deal a minimum of 20% damage (so I believe) to allow you to get a drop - A level of 80+ Range is highly recommended for killing him, unless you stand on the inside of the gate, you cannot use range pots unless the wildnerness has been changed to P2P - No XP is rewarded for killing him - He will say numerous messages throughout your time killing him and this is a basic understanding of what they mean; "Mortal strings and stones have no effect" - Range doesn't have any effect, "I fear not the magic of children" - Magic doesn't have any effect and "Your strength is *something, I forgot lol*" - Melee attacks have no effect.
I'm no expert by any stretch, but if you want to give it a go sometime, hit me up in game - Tha Playah and we can go through it.
Apologies about some of the wording regarding his phrases, I can't remember them word for word... But when you see it, you'll get the idea.