Small, but sometimes important, tactical tricks.

ICE, but when I hold down the Ctrl key, there's no reaction... they keep running as before... :( :( :(

I just checked. I hold down the left Ctrl key and, without releasing it, attack a slot, and everything works fine; the Furies stay in place. (Heroes version 1.5).

Added 6 minutes later
Well, since I've started revealing all the secrets, I'll continue. Playing as Haven. As soon as possible, upgrade peasants to militia (it's quite easy to do at the beginning of the game). We have militia and archers in our army. 1 slot for archers, 2 slots for the main mass of militia, and then divide the remaining slots with 1 unit of militia each. We arrange all our troops in a box, i.e., we protect the archers and the mass of militia with slots of 1 unit each. Method of killing: as soon as the enemies approach, we attack with a single unit; it dies, and then the entire army attacks. The trick is this: militia have a chance to stun, so in a normal scenario, the opponent won't be able to move much, as they will constantly be in a state of shock. This is a great way to clear the first 3 levels of mobs (except for archers and golems :).

Added 2 minutes later
In general, this tactic of dividing a unit with a special ability into the maximum possible number of slots works well for everyone, for example: zombies (they have the ability to reduce the attack and defense of the opponent), by attacking the opponent with 5-6 zombie slots, we reduce their parameters to 0-0 :), javelin throwers (ability "maim") the same tactic, etc.