Yes, young man, I don't play as a Witch Hunter – this combination of skills doesn't inspire me. First Strike is one of the most useful spells, practically for any monster, but it will be even more useful against Chaos Dragons with their fear ability. Of course, you need to be careful with Chaos Dragons so as not to harm your own units and lose fewer of them.

You're really missing out by not playing as a Witch Hunter :) I'm also not inspired by this combination of skills, but fear is a powerful thing. I remember when I was playing Heroes 5, I was able to defeat over 100 Griffins on my own with a hero of about the same level as a Witch Hunter, without using any potions of immortality. And even though this hero is weak in combat against other heroes, he levels up well on neutral creatures. Considering his Chivalry skill + leveling up Scouting, he doesn't need to be a combat hero and fight against combat heroes, but rather be a pure treasurer, focusing on neutral creatures and gathering resources from monsters. In general, for Lords, the Witch Hunter is the best build.
Why use First Strike against Chaos Dragons that don't have First Strike? They don't attack without retaliation; they just force you to retreat. And if the Chaos Dragons have First Strike, then Pikemen, Dragon Golems, and Goblin Knights with the ability to ignore First Strike are enough to prevent them from attacking first.
You also need to know how to deal with Hydras so that you don't attack them one at a time