With the predation of the termites on the lichens, the surviving species were either toxic or gaining enough mass to use combative mental mutations. The lichens had no minds to direct these attacks and thus the fliers as well as the termites were suffering.

In the end, it didn't matter as one of the avians brough back a nanobomb. It contained buggy nanites and when they were released, the avians, shadow keepers and lichens all suffered terribly. Some possible effects. The ML may want to reroll every hour, day or encounter (i.e. every time the PCs come back to the skyscraper) to represent how buggy the nanites were:

1 The nanites release a low level EMP, knocking powered artifacts offline until they leave the area (floors or even blocks).

2 The nanites turn carbon dioxide into carbonic acid and everything within contact with them takes 1 point of damage per minute.

3 The nanites strengthen the duracrete by converting some of the carbon lichen skeleton. Attempts to damage the walls with physical weapons fail.

4 All creatures within contact of the nanites age 1 year per hour.

5 Some of the carbon skeleton is converted to 1) high explosive, 2) toxic gas [class 3-5], 3) food useful to all species, 4) water, 5) fractal patterns that drive viewers insane or 6) charged power cells.

6 The nanites use a form of telepathy and give a secret to the PCs about something before the cataclysm.

7 The nanites convert biological waste into 1) ooze monsters, 2) bones, 3) statues of the PCs, 4) a powerful base (1 points of damage per round), 5) sticky silk or 6) glow in the dark pumpkins.

8 Everything within contact of the nanites is affected by a stasis field. It ends in 1) 1 hour, 2) 1 day, 3) 1 month, 4) 1 year, 5) 1 decade or 6) d6 centuries. Everything affected is indestructable until the effect ends.

9 A fog forms that passes through all matter but not force screens and force fields. It is created for d4 hours and the fog slowly settles through the levels below.

10 The nanites turn windows into small useful artifacts. 1) d4 power sources, 2) d6 medicinal artifacts, 3) d6 grenades, 4) d4 powered melee weapons, 5) d4 tools or 6) d8 foodstuffs.

Methods to remove the nanites from the PCs is up to the creativity of the ML and/or players.

The fungal allies in the basement had to deal with several mold invasions and a worm that tried to burrow into the fungi and lay its eggs. Not all the eggs were found.

The ice formations broke off and now float in midair, slowly orbiting the skyscraper. The amount of fly ash was increasing and collecting on the windows. The plants were starting to become concerned.