This is the only boss in Sporefall and is a single phase fight involving a lot of add management.
Normal/Heroic:
Start tanking the boss in the centre of the room.
Boss pulses constant and increasing raid wide damage - this eventually is the "soft enrage".
Putrid Fist: tank swap.
Awakening Fungi cast - multiple green circles with flowers, plus one blue with a mushroom. Pull boss to the blue circle.
Sporecap add spawns at blue circle - interrupt.
Smaller fixating adds spawn from green circles .. kite to Sporecap add and kill everything in a tight pack.
Mythic: Two different types of smaller fixating adds spawn from green circles. (If their corpses touch, a raid-wiping add appears). Kite near to Sporecap add and kill each type of add in their own tight pack, without getting too close.
Festering Vines: Green circle around players with reduced movement speed. Move to outside edge to drop.
After second Awakening Fungi, split raid odds/evens to each pile of add bodies.
Fungal Bloom: every add body becomes a bursting mushroom .. kill before they finish their casts.