So you have Yestabrod, myconid guards and gas spores. I put all these together to create a nice little combat challenge for my players. I only use a battlemap for important battles – be it narratively important or a big-boss life and death struggle. In this case, it was more narrative as I thought this encounter would give the party a blood nose but not kill them and they would be able to take a short rest straight after it.
Here is the battlemap I created for the Battle at the Garden of Horror (blue square is party start area).
FEATURES OF THE AREA
Illumination: Dim illumination, from luminescent fungal growths throughout the chamber.
Ceiling: The ceiling is 15 feet high over the lower elevation and 10 feet high above the higher elevations.
Elevation: The northern and southern portions of the room are 5 feet higher than the central area. The steep slopes can be climbed with a DC 7 Athletics check.
Ramps: These wooden ramps are difficult terrain, but they allow creatures to ascend or descend the steep slopes without making Athletics checks
Crystal Growth: Any creature adjacent to these 5-foot-tall reflective crystals while holding a light source is partially blinded by the glare,
taking a -2 penalty to attack rolls unless the creature has senses that do not require sight (such as tremorsense). The square containing crystal growth is blocking terrain.
The myconid gas spores attack without regard to their own safety. They try to stay within 15 feet of Yestabrod and the guards so that when they fall, their spore bursts will heal their allies.
The myconid guards also move in, using pacification spores at the first opportunity. They use roots of the colony to redirect damage from themselves to a gas spore so that its spore burst can damage enemies or heal other myconids.
Yestabrod rushes in to use rotting burst in the midst of the intruders. Then he relies on fungal slam attacks until rotting burst recharges when he become bloodied.
Once Yestabrod is felled the remaining myconids retreat back into the fungal undergrowth disappearing from view.
Tactically the idea was for the guards to use pacifying spores to lockdown as many characters as they could while Yestabrod used his AoE abilities to whittle them down. The gas spores would heal the plants and hurt the party when they exploded. Which the guards would try and do with their “Root of the Colony” ability whenever they could…. and it pretty much went that way.
Once the party felled Yestabrod the other myconids broke and ran. They also tried to keep the spores at bay by using ranged attacks to kill them. The guards were very effective at locking down two of the three melee fighters most of the battle.
I took the seed of the idea from a 4e encounter found in that editions Underdark source book.
Unfortunately, part 1 of the campaign ended the same session. The party pushed deeper into the mushroom cavern of Yggmorgus slowly becoming more and more disturbed (and insane) as they went in. After describing a mob of hundreds of fungal demon infused zombies they decided to lob a pot of lit oil into the middle of them. This triggered a zombie apocalypse scene which killed off the party. End of the campaign.
At least, part 1. They are planning to return as a different party for part 2 of Out of the Abyss.