Sumona

Sumona is a non-player character found in the north of Pollnivneach, near the Carpet transport spot. Talk to Sumona to begin the Smoking Kills quest.

After players complete the quest, Sumona reveals herself to be the newest Slayer master.

Talking to Catolax in the Smoke Dungeon after the quest will also reveal her and her twin "sister" to be The Devourer.

Her name is probably a reference to the term Summoner.

Here is an complete list of tasks she gives:
 * Aberrant Spectres
 * Abyssal Demons
 * Banshees (Including new ones below Pollnivneach)
 * Basilisks
 * Black Demons
 * Bloodvelds
 * Blue Dragons
 * Cave Crawlers
 * Cave Horrors
 * Dagannoths
 * Dust Devils
 * Elves
 * Fire Giants
 * Gargoyles
 * Greater Demons
 * Hellhounds
 * Iron Dragons
 * Kalphites
 * Kurasks
 * Nechryaels
 * Red Dragons
 * Scarabite Minions
 * Spiritual mages
 * spiritual warriors
 * Snakes
 * Terror dogs
 * Trolls
 * Turoth
 * Warped tortoises

Source
Compilation of Slayer tasks given by Sumona.