Can a creature grasped by Grasp of Hadar move with the Warlock?

Question

As a follow up to this question on Grasp of Hadar, I present the following situation. The warlock, under the fly spell's influence, sees the Dire Wolf knock the party's Rogue prone. It is now the Warlock's turn.
The warlock intends to pick up the Dire Wolf with Grasp of Hadar at point B, and if possible drop it off of the cliff when finishing movement for the Warlock's turn at point C. We know that we can move/attack/move in this edition per PHB Chapter 9. The other Q&A showed that Grasp can cause the Dire Wolf to fall once "moved 10' closesr" (up) to the flying Warlock with a successful Eldritch Blast / Grasp of Hadar hit. This might be a reach, but as it all happens on the Warlock's turn:

1. Does the Dire Wolf stay "10 feet closer" to the Warlock until the Warlock finished movement at point C and begin to fall at point Z?
   or
2. Can the Dire Wolf only begin its fall at point Y since Warlock picked it up at point B?

While I suspect that the answer is Case 2, something about how movement and attacks both happen during one's turn make me suspect that Case 1 is possible. Is it?

_{Attribution: pictures are jpg copies of Roll20 tokens of some humanoid, dire wolf, and commoner. I believe that this constitutes fair use).}

Answer 1

Grasp of Hadar does not grapple

Features do what they say they do. Grasp of Hadar says that

you can move that creature in a straight line 10 feet closer to you (XGtE 57)

You move it 10 feet once and that is it. There is no indication that the victim's position would be affected by the movement of the warlock.

You, however, can grapple

If you bring the target within reach with the spell, I personally would rule that you could attempt to grapple them in the same turn, preferably as the next thing you do. For this you will need a small trick (Action Surge or Quicken Spell) and proficiency in Athletics wouldn't go amiss, either.

Answer 2

The wolf will fall from point Y - the Eldritch Blast and the pull effect occur before your movement continues.

Movement and attacks both happen during a character's turn, but an attack occurs at one specific point in the character's movement.

According to the combat rules:

You can break up your Movement on Your Turn, using some of your speed before and after your action. For example, if you have a speed of 30 feet, you can move 10 feet, take your action, and then move 20 feet.

The rule specifies that you move, then attack, then move. (The next section about breaking movement in between multiple attacks is worded similarly.) The whole action is completed before you continue moving - the wolf is moved up to point Y, then falls, then you move.

Grappling has a specific rule allowing the character to move a grappled creature along with them; Grasp of Hadar has no such text, so it doesn't allow this manoeuvre.

Answer 3

No, it's an instantaneous pull

When you pull the wolf, you move it towards your position as if you where kicking him in the butt (or the opposite side of the wolf), not as a grapple. However, if you and/or your GM liked physics force problems at school, you could try to pull the wolf in a diagonal towards the cliff, calculate the pulling motion, discuss trigonometry... but I wouldn't rely on this thing too much if your group doesn't push enemies from cliffs too often.

Edit: It seems that Grasp of Hadar is caped to once on each turn on purpose, probably to prevent flying shenanigans and other not intended synergies, as opposed to Repelling Blast which can even prevent that your other beams get to your target. I think you already got the most of this Invocation mate :/

On another and completely unrelated note, I'm a little mad because I don't understand why Repelling Blast is treated differently, so if you still want to screw with positioning and don't fear your DM setting you on fire, pick a Halfling Warlock with Repelling Blast the next time. Halflings can pass through the space of any creature larger than them (like anyone can pass through the space of a non-hostile creature) and Mike Mearls said you can attack from an ally's space. You get between the legs of your enemy, shove them in the air, and laugh while running from your former friend xD