Delve - The Waterworks, Story: Put a Wrench on It!
New final boss: Shroomsprew (note the spelling, it's not Shroomspew as you would think, Blizzard probably spelled it wrong)

Abilities:
Fungal Charge - very fast cast time, try to sidestep it
Fungsplosion - causes the spores in the room to explode, dodge AOE
Fungalstorm - boss whirlwinds and chases you. Does high damage if caught.

Transcript: delve waterworks shroomsprew.zip

Screenshots

This looks like a copy and paste boss from another delve, how lazy of blizzard

Completed in 1c7c571