| You're lucky to have noticed this trap, for it would have released a cloud of deadly gas at you. Exactly what gas it holds, you cannot tell - perhaps it is plain poison, perhaps mutagenic fumes, perhaps flammable vapour, or perhaps something yet nastier.
"Good your grace, an' I had room for such a thundergust within my ancient bowels, 'tis not in reason I coulde discharge ye same and live to thank God for yt. He did choose handmaid so humble whereby to shew His power. Nay, 'tis not I have yt have brought forthe this rich o'ermastering fog, this fragrant gloom, so pray you seeke ye further."
-Mark Twain, "1601", 1880.
The gas trap is a dangerous and unpredictable trap found in the mid- to late-game. It holds a single charge of dangerous gas, which it releases as clouds when you step on it. Although not too dangerous if you have space to move away from the gas, they can be extremely dangerous if stepped on in tight quarters. They can be disarmed with the Traps skill, and flying characters will never trigger them.
Cloud types include:
Gas traps were removed in 0.13.
Gas traps were added to the game in 0.11.