Honestly, I like complicated ideas. Rather, seemingly complicated ideas.
As for how Black Lightning works...
Examples:
A plays Blue Crawler [3|3]. Blue Crawler attacks. A ends turn.
B draws and targets Blue Crawler [3|3] with Black Lightning. Ends turn.
A draws. Blue Crawler attacks. Black Lightning strikes it for 5 damage, but leaves it at 1 HP due to clause, and Blue Crawler [3|1] changes sides. A ends turn.
B draws. Blue Crawler [3|1] is now under his control. Blue Crawler attacks. Black Lightning strikes it for 5 damage, killing it since it is not at full health. B ends turn.
A plays Colossal Dragon [7|15]. Colossal Dragon attacks. A ends turn.
B draws and targets Colossal Dragon [7|15] with Black Lightning. Ends Turn.
A draws. Colossal Dragon attacks. Black Lightning strikes it for 5 damage and Colossal Dragon [7|10] changes sides. A ends turn.
B draws. Colossal Dragon [7|10] is now under his control. Colossal Dragon attacks. Black Lightning strikes it for 5 damage and Colossal Dragon [7|5] changes sides. Black Lightning ends. A ends turn.