Caution: Minor spoiler ahead, Out of the Abyss, hard cover.
The question is whether any level magic spell will act per usual on an artifact possessing very high-level magic, which is featured in a campaign, especially when the exposition of the artifact within the DM guide does not expressly limit the use of magic spells, etc., to influence or alter the artifact.
Background/specific example (spoiler)
In a above mentioned campaign, members of the party decided to pay another visit to the Maze Engine after time traveling. This time around, they used an Enlarge/Reduce spell (reduce 2 ton weight of ME to 1/8th = 500lbs), then Levitate (up to 500 lbs limit) to move the ME to a position on land where they could then activate it literally dozens of times to gain two ASIs. (I did the best that I could to opt out of what I saw as shenanigans, but was still affected).
I know, the DM can allow whatever he wants.
But are there generally applicable rules, express or implied, that delineate the power of spells beyond what the text of the spell or the campaign specifies? It seems obvious that there must be some 'common sense' limitation here, but this DM says that anything is possible, if not expressly prohibited.
Best Answer
There are many serious problems with this plan...
A lot of this is going into spoiler tags, because it reveals details of how things work behind the DM Screen.
First off....
It's almost certainly too heavy to Levitate, even while Reduced.
Levitate specifies that...
The Reduce factor of Enlarge/Reduce...
So, the maximum weight you can move with this combo is something that weighs 4,000 lbs.
The Maze Engine is described as
We will be charitable here. We will assume that the engine is about 75% hollow, accounting for the space between all the gears and arms and such.
Bronze has a density of 532 lbs per cubic foot. The Engine has a volume of 4,189 cubic feet.
So, going at 25% of the density of bronze (133 lbs/cubic foot)...
This thing weighs about 557,137 pounds. Or about 278 and a half tons.
Even if we assume that this thing is 90% hollow...we're still looking at it weighing 222,855 lbs.
Reducing the Engine would still leave it weighing 27,857 lbs. Far in excess of what Levitate can lift.
And, beyond even that...
This would take EXTREMELY precise timing.
if you cast Enlarge/Reduce on the Maze Engine...
The time it takes for something to fall a given distance can be computed with
$$ \sqrt{2\times\frac{height}{9.8}} $$
So, running the math with the numbers we have...
You probably should have all died from this, anyway.
The Maze Engine is NOT controllable.
If you guys got through this without all dying horribly, you are incredibly lucky.
During that time, each time it goes off it...
So, statistically speaking, in the amount of time it took you to get the two positive results you wanted...almost all of those things should have happened at least once, if not more.