There's no point in trying to go first. The tactic allows you to reach the opponent in the first round – that's its advantage. And if bears or hydras are positioned at the start in the center of the field, you can't escape them...

As far as I remember, in Expert Tactics, the deployment area isn't half the field, although I might be wrong. But even in this case, it won't change the turn order; your troops will still be attacked first, and with the same effectiveness (since you're in the middle of the field), they can reach you and strike first. So, there's no point in that.

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or protect the units you need, and also ensure proper positioning

Protect? And if I have dragons? You'll be doing me a favor, and I'll be happy about it. Unless there are units that attack two squares ahead.