Elves have high defence and excellent weapons - the level 84 warriors use the crystal pike (reach of a halberd, speed of a whip) and are weak to fire spells, while the level 89 warriors use crystal bows and are weak to crush.
Guthans works well here as hits more often so it heals you more often. Another popular method to kill Elves is to equip a Leaf-bladed sword and high prayer boosting armour (e.g. proselyte) whilst activating the "Protect Melee" prayer (reduces damages greatly). Players can easily recharge their prayer at the nearby altar after a few minutes of fighting.
Killing the elves in Lletya (this requires Mournings End Part 1 to be started) is more convenient than killing those in the Elf Camp as there is a nearby bank and altar, which is upstairs in the house where Arianwyn is located. However, only the elves in the Elf Camp drop charms. After completing Deadliest Catch a deposit chest is available south of the camp. Fishing spots and rabbits are nearby for replenishing food.
Elves live far longer than humans, and those that choose a military life have decades to hone skills that humans must train in months. As a result, elf warriors are among the most dangerous defenders of any town or city in RuneScape. They wield vicious pikes and crystal bows, but are weaker in the face of stabbing attacks.
Knowledge Base, Game Guide
Slayer Strategy
If you have 43+ prayer you can use protection prayers and restore your prayer points using the altar on the second floor. The ladder is located North of the bank.
A good strategy for killing elves efficiently (with 68+ summoning) is to use a combination of a Bunyip and protection prayers. Summon a Bunyip and kill elves in Lletya (requires starting Mourning's Ends Part I) until your life points get down to 400 or 500, then switch on the protection prayer required for the elf you are fighting. Use the protection prayer until your Bunyip recharges your life points to nearly full, then switch back to killing without a protection prayer until your life points are around 400 or 500 again. When you run out of prayer points, there is a Prayeraltar on the 1st floor (not ground floor) of the eastern-most building in Lletya. When your Bunyip has been used up, there is also a bank in Lletya. For this strategy to be most effective, a player will want a high prayer bonus and high range/meleedefence. If a player doesn't have 68 Summoning for a Bunyip familiar, then they might try a Regen bracelet and/or the Rapid Heal prayer. As far as a weapon goes, the ranged elves are weak to crush attacks so godswords, chaotic maul or drygore mace works well against them.
Some lower levelled players maybe find that the safest method is to use range or mage and use the fences and benches as safe spots. Be reminded that the elf warriors with pikes have a halberd's reach, so halberds should not be used due to the fact that they are very slow.
For faster slaying, there is a single Level 89 Elf Warrior on the same floor as the altar so you don't even need to climb up and down stairs. There is also a safespot in the entrace of Lletya, just beyond the bench.
Another alternative to complete this slayer task is to head over to the Elf Camp. This area has a fireplace as well as a fly fishing spot. Players can ultimately kill the elves there and stock up on their food supply by simply fishing.
This is one of the units to have been copied to FunOrb into Armies of Gielinor, although they are 2 different elf warrior units: elf archer and elf pikeman, in RuneScape they are still both called "Elf Warrior".
Chaeldar is apparently "Irritated Intensely" by elves and says "Slaughtering them is definitely a good thing". Sumona also seems to dislike the elves saying that "Their dedication to trees, bushes and music is an affront to me."
References
^Only elves in Lletya drop crystal teleport seeds. On rare occasions, a seed with one charge may be dropped, as opposed to an uncharged seed.