Allow players to donate 2 dark spells
With the new CC level adding another spell space, that allows someone to receive either 1 regular elixir spell, or two dark spells. However, if someone wants two dark spells, a single person can only donate 1 spell regardless of if its a dark or regular spell.
One person should be able to donate both spell spots, either a single regular elixir spell, or two dark spells. If thats not something you want in a normal situation, the ability to donate two dark spells should at least be a clan perk somewhere.