Level 50 Slayer is required to kill these and they give 120 slayer XP when assigned. They are found just before the entrance to the Aberrant spectre's lair. Bloodvelds are also known to drop a lot of green charms.
Charm Drop Rates
There are a number of safe spots around where you find these beasts. You can hide in corners and behind chairs and range, mage, or melee them from the safe spot you choose. They have low defence, attack, and strength, yet have very high life points. When training here, bring armour that defends magic; any form of dragonhide, Splitbark, or Mystic armour will suffice. If you can afford Guthans, it is very helpful here but can sometimes be tricky to use because it has negative Magic Defence and Bloodvelds are magic based. You may wish to use Bones to Peaches spell, as it will ensure that you remain for a long time. Protect from Melee is recommended, as their mage hits aren't very strong, unlike their melee hits.
The tongue of evil.
Rune med helm, Starved ancient effigy
Bones (1-3) (100%), Big bones (1-4), Coins (10-450), Fire rune (60), Blood rune (2-60), Death rune (7), Grimy herbs, Meat pizza, Gold ore, Steel hatchet, Steel scimitar, Steel full helm, Steel med helm, Black boots, Mithril chainbody, Mithril sq shield, Rune javelin (5), Nature talisman, Gold Charm, Green Charm, Crimson Charm, Blue Charm