"Weak demons"??

Let's do a small analysis: valery lost 12 Imps. And Lord lost more than three times as many. Therefore, I tend to favor the option with higher efficiency, even if it takes a little longer.

And I also want to note:
1. The strategy with Blood Drakes is perfectly viable even in the first week (unlike the Succubus strategy).
2. With Blood Drakes, you can defeat not only 30, but also many more mages (unlike the Succubus strategy).
3. Blood Drakes don't require a large number of resources (anticipating Lordesat's objections, I'll say right away that buying machines and upgrading Succubi on the hero is quite expensive and can backfire later, for example, there may not be enough sulfur to upgrade Dogs, which any slow infantry can easily defeat).