Ouroboros Flail (Greater)Weapon 17
Source Pathfinder Secrets of Magic
Damage 1d10 Bludgeoning
Type Martial
Price 15,000 gp
Weight 2 bulk
You can easily expand and contract the chain of this +3 greater striking greater extending war flail. It magically grows new links when extended and loses them when contracted.
Activate 
command
Frequency once per hour
Trigger You successfully Strike with the flail while activating its extending rune
Effect The head of the flail wraps around the target of the triggering Strike and drags it in your direction. The target must succeed at a DC 37 fortitude save or be pulled adjacent to you. A creature pulled in is then Grabbed by the flail until the end of your next turn unless you move, your target Escapes (DC 37), or you use the flail.
Activate 
Interact
Effect You extend the flail's chain, then wrap it across itself and strike two links together. This severs a usable 120-foot loop of chain from the flail, which instantly returns to its normal length. If you use this activation again, any previous chain you created with it disappears after 1 round. As with most obviously magical and temporary constructs, the chain cannot be sold.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
DisarmYou can use this weapon to Disarm with the Athletics skill even if you don't have a free hand. This uses the weapon's reach (if different from your own) and adds the weapon's item bonus to attack rolls (if any) as an item bonus to the Athletics check. If you critically fail a check to Disarm using the weapon, you can drop the weapon to take the effects of a failure instead of a critical failure. On a critical success, you still need a free hand if you want to take the item.
MagicalSomething with the magical trait is imbued with magical energies not tied to a specific tradition of magic. A magical item radiates a magic aura infused with its dominant school of magic. Some items or effects are closely tied to a particular tradition of magic. In these cases, the item has the arcane, divine, occult, or primal trait instead of the magical trait. Any of these traits indicate that the item is magical.
SweepThis weapon makes wide sweeping or spinning attacks, making it easier to attack multiple enemies. When you attack with this weapon, you gain a +1 circumstance bonus to your attack roll if you already attempted to attack a different target this turn using this weapon.
TransmutationEffects and magic items with this trait are associated with the transmutation school of magic, typically changing something's form.
TripYou can use this weapon to Trip with the Athletics skill even if you don't have a free hand. This uses the weapon's reach (if different from your own) and adds the weapon's item bonus to attack rolls as an item bonus to the Athletics check. If you critically fail a check to Trip using the weapon, you can drop the weapon to take the effects of a failure instead of a critical failure.