I know creatures can squeeze so if I am a large creature I can squeeze my way through a 5-foot square hall spending 1 extra foot for every foot it moves there. But, can a large creature ends its movement on a less than 10 foot square such as 1, 2, or 3 5-foot squares together (cases A, B, C below)? If it can then it has disadvantage on attack rolls and Dexterity saving throws and attack rolls against the creature have advantage while it’s in the smaller space, right?
So what if the large creature is amorphous (like oozes)? It ignores the extra foot cost for squeezing for sure according to RAW, but what about the other penalties if it ends its movement on a smaller square? I just wonder if oozes can end their movement on 5, 5x2 and 5x3 (case A, B, C below) squares with impunity
O: available space,
X: unavailable space
Case A: 5-foot square:
╔═══╦═══╗ ║ O ║ X ║ ╠═══╬═══╣ ║ X ║ X ║ ╚═══╩═══╝
Case B: 2 5-foot squares:
╔═══╦═══╗ ║ O ║ O ║ ╠═══╬═══╣ ║ X ║ X ║ ╚═══╩═══╝
Case C: 3 5-foot squares:
╔═══╦═══╗ ║ O ║ O ║ ╠═══╬═══╣ ║ X ║ O ║ ╚═══╩═══╝
Case D: 10 foot square:
╔═══╦═══╗ ║ O ║ O ║ ╠═══╬═══╣ ║ O ║ O ║ ╚═══╩═══╝
Can a large creature finish its movement in Case A, B, or C?
We deal with surface areas not volumes in D&D. If the height of a ceiling is shorter than the height of a large creature, then the DM should apply the squeezing condition regardless of the fact that it fills 10 square feet.