Veil of the Evoked

"A shimmering, gelatinous wall of viscous, cold black energy curtains from the corners of a doorway, spreading inward like syrup unaffected by gravity."

A near-impenetrable wall of arcane energy forms in a doorway of at least 2x1, and at most 6x12 (an extra spell slot or two can be expended to fit larger or smaller doors; DM's discretion).

It can be dispelled by the caster at will, but to be forcibly dispel it, the opposing caster must surpass the original caster's Spell Save DC (default DC of 17, if somehow implemented by a non-caster).