Draconid Sovereign Template
Only a true dragon can transform into a Draconid Sovereign, and requires far more ideal conditions than creating a Spore Servant from a corpse. The dragon must be infected with spores during its most vulnerable period - the long torpor of a true dragon as it sheds its scales and advances in age. Intentional or not, the result of mixing the dragon's ageless dreams and the myconid hive mind is dramatic - myconid spores hijack and aggressively mutate the dragon's body, even as its powerful soul infects nearby myconids.
The result is a terrifying beast of two worlds, capable of overriding even a myconid sovereign's commands. The dragon has all the tyrannical and greedy habits of its species, but is now devoted to expanding its fungal empire at any cost. It hoards fertile earth, crystals, and corpses instead of gold, and prefers to kill and reanimate mortal tresspassers, the better to expand the hive mind's reach.
When a dragon becomes a Draconid Sovereign, it retains its statistics except as described below. The dragon might retain or lose any or all of its lair actions or inherit new ones, as the DM sees fit.
Type. The dragon's type is plant.
Senses. The dragon's Blindsight range is tripled, and it is blind beyond this radius.
Conditional Immunities. The dragon can't be blinded, charmed, frightened, poisoned, or paralyzed.
Damage Resistances. The dragon has immunity to poison damage.
Spores. The dragon has all of the Spore abilities of a Myconid Sovereign, but their ranges are tripled and any DCs are the same as its breath weapon.
Myconid Miasma. The dragon constantly exhudes a yellowish mist from fluted growths on its back. This mist makes 30 feet in all directions lightly obscured.
Spore Cloud Breath. The dragon loses its original breath weapons. Instead, any damaging breath weapon it had deals poison damage (other statistics remain the same). It also gains a second breath weapon of paralyzing spores, like a silver dragon's paralysis breath of the same age category.
Hoard of the Dragonmind. Any corpse of a flesh and blood creature within 30 feet of the dragon rises as a Spore Servant at the start of the dragon's next turn. A number of corpses can be raised in this way each turn equal to the dragon's CR.
Sun Sickness. While in sunlight, the dragon has disadvantage on ability checks, attack rolls, and saving throws. The dragon dies if it spends more than 1 hour in direct sunlight.