This spell is a class spell for clerics and druids.

7th-level evocation
Casting Time: 1 action
Range: Self (300 ft. line)
Components: V, S, M (an enokitake spore)
Duration: Instantaneous

You spew forth a line of green energy from your mouth in a line 300 feet long and 5 feet wide. Each flesh-and-blood creature in that line must succeed on a Dexterity saving throw or take 20d6 poison damage, or half as much on a success. The bodies of creatures slain by this damage explode into spores that form an enokitake child in 2d6 hours. Enokitake created by this spell are initially friendly toward you and your allies.

Ref: TPKB1 p104