The Seercull is a Fremennik bow. Similar to the magic shortbow, it requires a Ranged level of 50 to wield, and can fire standard arrows up to rune, as well as Broad Arrows. The attack range of the Seercull is 7 spaces.
The bow's name can be attributed to the combination of the words seer (another word for "mage" or "wizard") and cull(another word for "kill"). In other words, the termed mage-killer is consistent with its examine info, which states that the bow was used to kill Moon Clan members, who were mages.
The special attack definitely lives up to it's name. The special attack does normal damage but reduces the opponent's magic level by the amount dealt. It can have disastrous effects on the magic user. A 10 hit splat would cause10 magic levels lost, preventing the enemy player from casting the spells he wants to cast. Often times, mages only carry runes for one spell, and become completely defenseless when hit by Seercull. Still, because the bow is expensive, it is often only used in minigames.
Barragers -Perfect target-Edit
Even with 99 magic, barragers are extremely vulnerable to Seercull, as Ice barrage requires 94 magic. Usually wearing ahrims, it is easy to land a 15 on these guys and send their minds to oblivion.
God Spell/Teleblockers -Weak target-Edit
You may prevent them from using entangle, and charging a second time. They still have bind and charge lasts 5 minutes. You can prevent a teleblock if you use the special in the opening of the battle, and he will likely attempt to flee.
Lunars -Weak target-Edit
You can easily prevent the enemy player from using vengeance.
The Seercull is obtainable only as a rare drop from Daganoth Supreme, or by buying it from another player. It appears to be a recurve bow. It is not commonly seen amongst players due to the magic shortbow being much cheaper and easier to obtain.