I'm running a game with variant encumbrance, and I'm wondering how the monsters would be affected. Obviously, heavily armed and armoured enemies would be hampered, but what about "drug and drag" monsters like the grell?
A grell's attack strategy is written out under its stat block, showing it to be an ambush predator (MM, p. 172):
Floating Ambushers. A grell prefers to ambush lone creatures or stragglers, hovering silently near the ceiling of a passage or cavern until a suitable target passes below, whereupon it descends quickly and wraps its tentacles around its prey. It then floats away to its lair with the paralyzed creature in its clutches.
The grell paralyzes and floats away with its prey in its tentacles:
Tentacles. Melee Weapon Attack: +4 to hit, reach 10 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must succeed on a DC 11 Constitution saving throw or be poisoned for 1 minute. The poisoned target is paralyzed, and it can repeat the saving throw at the end of each of its turns, ending the effect on a success.
The target is also grappled (escape DC 15). If the target is Medium or smaller, it is also restrained until this grapple ends. While grappling the target, the grell has advantage on attack rolls against it and can’t use this attack against other targets. When the grell moves, any Medium or smaller target it is grappling moves with it.
The variant encumbrance rules state:
If you carry weight in excess of 5 times your Strength score, you are encumbered, which means your speed drops by 10 feet.
If you carry weight in excess of 10 times your Strength score, up to your maximum carrying capacity [15 times your Strength score], you are instead heavily encumbered, which means your speed drops by 20 feet and you have disadvantage on ability checks, attack rolls, and saving throws that use Strength, Dexterity, or Constitution.
The Push, Drag, or Lift rules are also important here:
You can push, drag, or lift a weight in pounds up to twice your carrying capacity (or 30 times your Strength score). While pushing or dragging weight in excess of your carrying capacity, your speed drops to 5 feet.
The grell has a fly speed of 30 ft. (hover) and a STR of 15. This means that the grell's encumbrance thresholds are 75 lbs. for being encumbered (reduced to a 20-ft. fly speed), 150 lbs. for being heavily encumbered (reduced to a 10-ft. fly speed and many other penalties), 225 lbs. for its max carrying capacity (0-ft. fly speed?), and 450 lbs. for the maximum weight it can push/drag/lift (5-ft. fly speed when above carrying capacity).
Is this right? Or am I missing a rule somewhere about hover speeds interacting with carry weight differently?
Anything larger than a frail human wizard (plus equipment) knocks its speed to 10 ft. and imposes a lot of penalties – which, while deliciously thematic and a great visual, seems like a pretty heavy nerf to the monster.