Herder's Hook(5e): Unique Polearm Ation/Effect/Attack

[Wyrmmwood]

Hello

I'm just getting into NPC action/attacks(5e) and have come across a homebrew weapon for a centaur NPC that's likely going to appear quite often in the game.
I'd like to have FG calculate Herder's Hook for the game. Any help, suggestions, tweaks...etc are welcome.

Herder's Hook:

• A large polearm with a spiked end, and a curved blade that bends back toward the wielder (a hook)
• Aside from the normal uses of a polearm, I'd like the centaur to 'collar' (restrain/grapple...etc) around the neck of opponents. This would require a successful attack with a higher difficulty.
• 'Collared' opponents would have a roll to free themselves and have an Effect while collared.
• An optional 'Dragging' attack/action on collared opponents who are medium or smaller, for large wielders of Herder's Hook. Taking automatic damage while dragged & collared, although the curved blade isn't sharpened on the inside to slice/slash.

P.S. If I've overlooked an obvious answer, please just point me in the right direction.

Ok, so....
I've considered an Effect to create to put on 'collared' opponents. FG could apply the Effect itself.
I figure some kind of save vs restraint to avoid 'collaring', which FG could do as well.
An ability check, each round, to free oneself from the 'collaring', although some of the "collared' may forego trying to free themselves. So having the Effect only last until the check/turn is successful, is a factor.
Automatic damage should be straight forward, which is likely bludgeoning.

Context:
Herder Morse, a lone 'reluctant settler' centaur who tends to local wild herds, as a service to nearby settlements(Dwarven/Human) who rely on the food source. He deals with nearby hostile humanoid(Goblin/Hobgoblin) populations and a favoured tactic is to 'collar' an enemy and drag him to their death across the open tundra. Especially within view of their companions.
Herder Morse will play a large role in the PCs activities/environment and will likely interact in many combat situations with the PCs.

[Zacchaeus]

Hi,Wyrmmwood, welcome to FG.

What you are describing is very similar to the kind of attacks certain NPCs make where they make an attack roll which initialy causes damage and then the target needs to make a save or be grappled.

So you would describe that in an NPC action as something like this:

Herder's Hook. Melee weapon attack: +x to hit, reach 10 ft., one target. Hit: nxn + n bludgeoning damage and the target must make a DC x <ability> saving throw. On a failure the target is grappled (DC x to escape). Whilst grappled in this way the target takes ndn bludgeoning damage at the start of each of its turns.

[Wyrmmwood]

Hey thx Zacchaeus. That works.
I added a separate Dragging Action, for damage(automatic hit) as the NPCs choice. And kept the minimal on going damage if the enemy is merely being grappled, but not being dragged.