Playing a 5e campaign, DM insists Gaseous Form cannot be cast on the caster because s/he cannot maintain concentration while in gaseous form. He mentioned not being able to find any opinions permitting this online and ruled it had to be cast on other beings while the caster maintained the spell.
My feeling is that it's commonly accepted that one of the main uses of Gaseous Form is as an escape spell (which is why there aren't any threads about this), and not being able to cast it on one's self defeats this purpose, even with the new Concentration mechanic in 5e. Thoughts?
Best Answer
Yes, the caster can cast Gaseous Form on himself and maintain concentration.
There's nothing in the spell Gaseous Form that would break or stop concentration. There's nothing in the rules about concentration that would indicate that entering a gaseous form would end or break concentration.
The general rule is that a caster can maintain concentration until the spell duration ends, or it is broken by damage or unconsciousness or by casting a new spell that requires it. This general rule is not contradicted or superceded by any more specific rule in or regarding the spell Gaseous Form.