I want to make a magic bolas for the 3 fantasy games we support, but first I have to mundane version, since it doesn’t exist for two of them. It already exists for Pathfinder, and 13th Age has rules for weapons for each class so it will just be a magic item. So here’s the 5e version.
Bolas 2 gp — 1 lb. Special, thrown (range 20/60)
Bolas: When hit with a bolas, the target becomes grappled. If the hit is a critical hit, the target is grappled and prone. The target can use their action to free themself with a DC 10 Strength check. Alternatively, the target or another creature can deal 5 damage to the bolas (AC 10). Attacking the bolas in this manner deals no damage to the grappled creature. Bolas cannot grapple creatures that can move through narrow spaces like an air elemental or a grey ooze or are otherwise formless.