From The Heroes of Might and Magic III wiki

Town: Neutral

[[Image: ]]	Attack Skill	30	Damage	50
	Defense Skill	30	Health	750
	Speed	17	Shots	0
	Growth	1	Cost	15000 gold + 14 sulfur
Special: Acid Breath+Counts as dragon

[edit] Dwelling

Rust Dragon is recruited in Sulfurous Lair.

[edit] Upgrading

Can't be upgraded.