You pull wisps of shadow material from the Shadowfell to create a nonliving object of vegetable matter within range: soft goods, rope, wood, or something similar. You can also use this spell to create mineral objects such as stone, crystal, or metal. The object created must be no larger than a 5-foot cube, and the object must be of a form and material that you have seen before.
The duration depends on the object's material. If the object is composed of multiple materials, use the shortest duration.
Material
Duration
Vegetable matter
1 day
Stone or crystal
12 hours
Precious metals
1 hour
Gems
10 minutes
Adamantine or mithral
1 minute
Using any material created by this spell as another spell's material component causes that spell to fail.
At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the cube increases by 5 feet for each slot level above 5th.
How much damage would a 5x5 cube of adamantine do if it fell from 30ft above an enemy?
What about at 9th level, where it will be a 25x25 cube?
Creation isn't really a combat spell, as it takes a minute to cast, and most combats are over after 1 minute, plus the spells 30 foot range would not allow for great positioning of yourself to not also be struck by the object, especially if cast at 9th level.
But, if you were to manage to concentrate casting for 1 minute and successfully create the adamantine cube over the head of the creature in question, I would rule as follows (note this is entirely homebrew, and your DM may differ):
Using the Rolling Sphere trap from the DMG as a start point, we will say a level six casting (10x10 cube) would deal the same damage, so 10d10 (avg 55). While weight would scale by 8 as the cube halves and doubles, you don't really want to be rolling that many dice at 9th level, so we will instead use a linear scaling, down to 5d10 (avg 27) for the base level five spell, and up to 15d10 (82), 20d10 (110), and 25d10 (137) damage for the 7th, 8th, and 9th level respectively. I would also allow the creature(s) under the cube to made a dex save for 1/2 damage.
The chart for improvised damage in the DMG has 4d10 for collapsing rubble (5×5×5 I'd say), 10d10 for crushed by walls (10×10×10 I'd say), 18d10 for hit by flying fortress (>100×100×100 at least), and 24d10 for crunched by moon sized monster (so much bigger).
Honestly, I don't think these values scale well. Icon's house rule scale is probably more fair, but might overshoot a bit. Meteor swarm does 20d6 bludgeoning damage for a 80 feet diameter sphere (granted it also does the same amount of fire damage).
You pull wisps of shadow material from the Shadowfell to create a nonliving object of vegetable matter within range: soft goods, rope, wood, or something similar. You can also use this spell to create mineral objects such as stone, crystal, or metal. The object created must be no larger than a 5-foot cube, and the object must be of a form and material that you have seen before.
The duration depends on the object's material. If the object is composed of multiple materials, use the shortest duration.
Using any material created by this spell as another spell's material component causes that spell to fail.
At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the cube increases by 5 feet for each slot level above 5th.
How much damage would a 5x5 cube of adamantine do if it fell from 30ft above an enemy?
What about at 9th level, where it will be a 25x25 cube?
Creation isn't really a combat spell, as it takes a minute to cast, and most combats are over after 1 minute, plus the spells 30 foot range would not allow for great positioning of yourself to not also be struck by the object, especially if cast at 9th level.
But, if you were to manage to concentrate casting for 1 minute and successfully create the adamantine cube over the head of the creature in question, I would rule as follows (note this is entirely homebrew, and your DM may differ):
Using the Rolling Sphere trap from the DMG as a start point, we will say a level six casting (10x10 cube) would deal the same damage, so 10d10 (avg 55). While weight would scale by 8 as the cube halves and doubles, you don't really want to be rolling that many dice at 9th level, so we will instead use a linear scaling, down to 5d10 (avg 27) for the base level five spell, and up to 15d10 (82), 20d10 (110), and 25d10 (137) damage for the 7th, 8th, and 9th level respectively. I would also allow the creature(s) under the cube to made a dex save for 1/2 damage.
The chart for improvised damage in the DMG has 4d10 for collapsing rubble (5×5×5 I'd say), 10d10 for crushed by walls (10×10×10 I'd say), 18d10 for hit by flying fortress (>100×100×100 at least), and 24d10 for crunched by moon sized monster (so much bigger).
Honestly, I don't think these values scale well. Icon's house rule scale is probably more fair, but might overshoot a bit. Meteor swarm does 20d6 bludgeoning damage for a 80 feet diameter sphere (granted it also does the same amount of fire damage).