Abyssal Demons are Level 124 NPC's that are very popular for new players that have a high enough combat level because of their drops, as well as decent combat XP. You can access Abyssal Demons VIA Training Teleport > Slayer Tower. Floor 3.
Note: Always use a Ring of Wealth to increase your chances of better drops.
Abyssal Whip - 0.78% Chance. (5-8m each)
Uncut Dragonstone - 0.78% Chance. (Which can be made into Ring of Wealth)
Coins - 50% Chance. (Up to 100,000 coins per drop)
Infernal Ashes - 100% Chance. (Useless)
Blue Charm - 1.01% Chance.
Green Charm - 4.16% Chance.
Gold Charm - 8.33% Chance.
Crimson Charm - 33.33% Chance.
Along with lots of other random drops like Dragon Medium Helm, Rune parts, Pure Essense,