How does simic hybrid grappling work?

[Greywander]

Grappling Appendages (5th level). You have two special appendages growing alongside with your arms. Choose whether they're both claws or tentacles. As an action, you can use one of them to grapple a creature. Each one is also a natural weapon, which you can use to make an unarmed strike with. If you hit, they do 1D6 + your strength modifier bludgeon damage. Immediately after hitting, you can try to grapple the target as a bonus action. These appendages are not dexterous enough to use weapons, magic weapons, and other specialized equipment.
So let me see if I understand this. Let's say I'm a class with Extra Attack. I can choose to give up all of my attacks in order to make one grappling attempt. Or, I can make two attacks with my appendages and then as long as I hit at least once I can use a bonus action to try and grapple. I suppose an enemy could have high AC but low Athletics/Acrobatics, so there may be times where it's easier to skip the attack and go straight to the grapple check.

But my question is, why can't I just replace one of my normal Attack action attacks with a grapple attempt? Why bother with the "as an action" instead of just saying that you can use the appendage in place of a free hand for grappling? Can you not grapple with them except using a full action or using the special bonus action? It just seems like the intention and the execution aren't quite matching up.

If a DM let you grapple with them normally, then a simic hybrid Rune Knight would be a fun build to try. Being able to grapple two targets while using a weapon and shield, or three targets with just a shield, or four targets if you ditch the shield too, while also being able to grow to a huge size, that would be pretty terrifying. Now you just need a way to fly and then nothing will be safe from you.

[Beni-Kujaku]

As written, you can only initiate a grapple with one of your claws if you have hit something with it in the case of an Attack Action, or if you use your action just for that. It doesn't say that the appendages count as free hands, so you can't technically replace one of your attacks with a grapple. If you want, you may fluff that as the claws being clumsy, and either you can choose to brutally grapple the opponent but losing precision (you need an attack roll, but you deal damage), or being precise, but needing a full action for that.

However, since they are litterally called grappling appendages, you may ask your DM beforehand if they would let you replace one of your attacks with a grapple, and I believe it was the original intent, even though what is written doesn't allow it.

[Unoriginal]

So let me see if I understand this. Let's say I'm a class with Extra Attack. I can choose to give up all of my attacks in order to make one grappling attempt. Or, I can make two attacks with my appendages and then as long as I hit at least once I can use a bonus action to try and grapple. I suppose an enemy could have high AC but low Athletics/Acrobatics, so there may be times where it's easier to skip the attack and go straight to the grapple check.

But my question is, why can't I just replace one of my normal Attack action attacks with a grapple attempt? Why bother with the "as an action" instead of just saying that you can use the appendage in place of a free hand for grappling? Can you not grapple with them except using a full action or using the special bonus action? It just seems like the intention and the execution aren't quite matching up.

If a DM let you grapple with them normally, then a simic hybrid Rune Knight would be a fun build to try. Being able to grapple two targets while using a weapon and shield, or three targets with just a shield, or four targets if you ditch the shield too, while also being able to grow to a huge size, that would be pretty terrifying. Now you just need a way to fly and then nothing will be safe from you.

The Simic Hybrid's tentacles/claws give you a special action that let you make one unarmed strike with said tentacles/claws. If you hit, you can grapple with them.

This special action is not affected by Extra attacks or the like.

You can also do regular grappling with the Attack action, but not with your claws/tentacles.

[cookieface]

Having four arms is a big deal, so this seems like a governor to prevent being able to grapple everything on the battlefield all at once.

You'll already gain the benefit of shield plus weapon plus grapple (or two-handed weapon plus grapple) so this limits ability to abuse that by forcing one grapple per turn.

That said, if one of my players wanted a Simic grappler build, I'd be cool with allowing grapples as part of the attack action as usual.

[Greywander]

The Simic Hybrid's tentacles/claws give you a special action that let you make one unarmed strike with said tentacles/claws. If you hit, you can grapple with them.

This special action is not affected by Extra attacks or the like.
Where are you seeing this? It lets you use an action to grapple, but simply attacking with them uses the normal Attack action and thus is affected by Extra Attack.

It seems like we can maximize our grappling by taking the Attack action and attacking once with an appendage. On a hit, we BA grapple. Hit or miss, we use our second attack to grapple using a free hand or shove the enemy we just grappled prone. Under ideal circumstances, we can get one attack in while also grappling and shoving prone one enemy, or grappling two enemies. It's basically free Tavern Brawler.

With the fighter, it gets even better. Once we have all four attacks it would look something like this: Attack with appended, BA grapple on a hit. Use second attack to shove prone. Use third attack to grapple with a free hand. Use fourth attack to shove prone. We get one attack in while grappling and shoving prone two enemies, so if we're fighting barehanded we can have four enemies grappled and shoved prone by our second turn.

I wonder, are you still able to use the appendages as natural weapon while they're grappling a target? It would make sense that you could use them to squeeze a grappled target, but perhaps not to attack a different target.