Superior slayer monster

Superior slayer monsters are more powerful versions of normal slayer monsters that have a 1/200 chance to spawn upon the death of one of its normal counterparts. They can be encountered after purchasing the unlock Bigger and Badder for 150 Slayer reward points from any Slayer master, and will only occur while on a Slayer task. This can be toggled on and off afterwards without loss of points.

When a superior slayer monster spawns, a message will appear in the chatbox, stating "A superior foe has appeared..." Killing a superior slayer monster will reward players with a generous amount of Slayer experience — for most, but not all of them, this is about ten times the Hitpoints of the superior monster. This experience will even be granted if the superior monster is slain after the completion of the corresponding Slayer task.

They will also give three rolls on their lesser counterpart's drop table. Once a superior slayer monster has spawned it is only attackable by the spawning player. A superior monster will despawn in two minutes if the player stays in the vicinity and does not attack it, or less than 30 seconds if they leave the area. Should the player die while fighting it or teleport away, the monster will despawn soon after.

In addition, once one has appeared, another one will not spawn for that player until it is killed or despawns. In single combat areas, a superior slayer monster can be attacked even if you are under attack by another monster; when this happens, the standard monster will stop attacking you. In multicombat areas, it is possible for multiple superior slayer monsters to appear simultaneously if multiple monsters are killed at the same time.

Drops
Superior slayer monsters are guaranteed to drop an ensouled head (if applicable) and dark totem pieces (when killing one within the Catacombs of Kourend). Players are also ten times more likely to receive a clue scroll from killing one. In addition, superior slayer monsters have four unique drops shared among all superior slayer monsters:
 * Imbued heart, which boosts the player's Magic level by 1 + 10% of your Magic level every seven minutes.
 * Dust battlestaff, which when equipped provides an infinite amount of air and earth runes.
 * Mist battlestaff, which when equipped provides an infinite amount of air and water runes.
 * Eternal gem, which can be crafted into an eternal slayer ring.

Drop rate
The chance of rolling the unique drop table (UDT) is $$\frac{1}{200 - \frac{(SlayerReq+55)^2}{125}}$$

If the players rolls the unique drop table, there is then a 1/8 chance each of receiving an imbued heart or eternal gem, and a 3/8 chance each of receiving one of the battlestaves.

Thus, the formula of receiving an imbued heart or eternal gem is $$\frac{1}{8* (200-\frac{(Slayer Req+55)^2}{125})}$$

And the formula of receiving a dust or mist battlestave is $$\frac{1}{\frac{8}{3}*(200-\frac{(Slayer Req+55)^2}{125})}$$

Monsters
There are superior versions of the following monsters: