Tainted Shardling (5e Template)
From D&D Wiki
Because shardlings are very attuned to mental energy, a shift can disturb their personality and psionic abilities. If a shardling stayed around a portal to the Lower Planes or a group of bloodthirsty demons, for example, then it would eventually begin to take on their attributes as it is permanently infused with negative energy. They also change colours, from their natural green to a sickly black.
Hit Dice. Increase the tainted shardling's hit dice by 2.
Languages. The tainted shardling learns Abyssal and Infernal.
Damage Immunities. The tainted shardling becomes immune to necrotic damage.
Alignment. The tainted shardling's alignment changes to chaotic evil.
Innate Spellcasting (Psionics). The tainted shardling adds the following spells to its Innate Spellcasting.
Magic Resistance. The clockwork construct has advantage on saving throws against spells and other magical effects.
Multiattack. The tainted shardling makes all its normal attacks, followed by a Dark Beam.
Recalculate the creature's CR with the following considerations:
- Increased hit points (from improved hit dice).
- Immunity to necrotic damage.
- Increase effective AC by 2 (from Magic Resistance).
- Increase per-round damage by the amount listed in the trait (from Dark Beam).