Black Mist
For several weeks, massively reduces the target's solar collectors efficiency, cumulative

Week 24, year 0
Your psychics are casting Black Mist on Evil Empire of family #3.
Your psychics successfully stayed undiscovered while performing the spell.
A dense mist is spreading around the target's planets, your psychics estimate solar collectors efficiency has been reduced by 25 %.

(Note: results may vary depending on the size of your/enemy empire and your/enemy number of agents)