Blightcore Meltdown

8th-level conjuration (sorcerer, wizard)

Casting Time: 1 action

Range: 100 feet

Components: V, S, M (powdered bloodstone worth 100 gp)

Duration: Concentration, up to 1 minute

You create a coruscating mass of blightburn crystal that pulsates with a bright green radiance, casting deadly emanations throughout the area. Each round a creature begins its turn within the blightcore meltdown, it takes 2d6 points of fire damage and must succeed on a Constitution saving throw or contract blightburn sickness.

Disease: Blightburn Sickness. A creature makes an initial Constitution saving throw to contract the disease (above) and any subsequent Constitution saving throws are at DC 20. At the end of its next long rest, a creature with this disease makes its saving throw or lowers its Constitution and Charisma scores by 1. A creature naturally fights off this disease by making 2 consecutive successful saving throws to resist it.

Creatures protected by a force effect (such as mage armor or shield) take only half damage and gain temporary immunity to blightburn sickness for a number of rounds equal to the spell level of the force effect they are using. After this time, the blightburn radiation penetrates the force effect and creatures within are exposed to full damage and blightburn sickness, though they have advantage on their saving throw against contracting the disease. If a creature is using multiple force effects, add the total spell levels of all force effects to determine how long it takes the blightburn radiation to penetrate.

The presence of the blightcore meltdown interferes with teleportation effects of all kinds, including not only actual teleportation but also planar travel and calling and summoning effects. Any such effect cast within–or cast so as to cause creatures to appear within–the area of a blightburn meltdown requires an ability check (1d20 + the opposing spellcaster’s spellcasting ability modifier) against a DC of 15 + your spellcasting ability modifier or the effect fails.

Finally, a blightcore meltdown greatly enhances polymorph effects or effects that alter the size of a living target within the area. The targets of such effects have disadvantage on their saving throws but gain double their normal benefit (shrinking twice in size if reduced, doubling in size if enlarged, etc.)

Such effects are more tenacious and difficult to remove as well, causing checks made to dispel or remove them to have disadvantage.