Scorpior is trash. Even though I usually play as Dungeon, I don't see any arguments in their favor, and there can't be any, except for their appearance, but is that what this is about? Even the Wyvern, due to its cost and the houses with Stryx, is better.
Regarding the Naga and Dread Knight. The latter has a great double damage ability, but it's a gamble - it might work well, or it might not? The Naga is simply an uber unit with 30 damage (OMG, like a Tier 7 unit :eek:) and no retaliation!! Sorry, but in any battle, against anyone, under any circumstances, that's a huge advantage.