Lightning Lure pulls a creature toward you:
You create a lash of lightning energy that strikes at one creature of
your choice that you can see within range. The target must succeed on
a Strength saving throw or be pulled up to 10 feet in a straight line
toward you and then take 1d8 lightning damage if it is within 5 feet
of you. (Sword Coast Adventurer's Guide, p. 143)
Does lightning lure pull a creature toward you regardless of other circumstances?
For instance, if you're chained by the wrist to an immovable object, does lightning lure pull until something gives, perhaps your wrist?
My own thinking is that the RAW does not address anything like this, so it is up to the GM's judgement.
I would like to know if this is a reasonable interpretation or alternatively, what might be a reasonable ruling.
Best Answer
Does lightning lure pull a creature toward you regardless of other circumstances?
No. The key words here "up to 10 feet" If something prevents it from being pulled, that would pull it 0 feet, which is included in up to 10 feet. Likewise, if there is suddenly a wall 5 feet away from the creature between you and it, it would stop when it hits the stone wall. They still roll the save, and on fail they move 0 feet but if they are within the distance, they still take the damage. That is my interpretation of the RAW.
I'd argue that grappled is muddier and that would require a DM call. The question is what is stronger the grappler's hold on the target or the spell. I'd personally rule that when the target makes a failed save, a contested roll be made between the spell caster's spell attack modifier and the grapperler's strength roll.