Best level 6 unit.

It's a shame, guys, that no one thought about the fact that manticores can fly. When you take a city, they are more useful than all the "walking" units. Wyverns too. Besides, wyverns can actually be built at the very beginning. And if their rare poison works, it can be quite unpleasant. Cyclops also shoot. But still, Dark Knights are indeed the strongest. There can be no argument about that. Fast, with a curse, double damage, powerful combat abilities – all this makes them the strongest at level 6.
Well, unicorns are also good. Blindness doesn't happen that often, and that's why they can be very effective sometimes. In general, everyone has their own drawbacks, but the Dark Knights are the strongest.