Tactics for Rampart.

I haven't played online yet. But I play on randomly generated maps without turn-based gameplay like in online mode.
And there were cases when I took several dragon utopias, but I didn't pay much attention to knowledge and magic, while my opponent had very well-developed magic and knowledge.

How will slowing down and speeding up help against elementals? Will I slow them down and just wait? The AI will summon stacks of 7 (this has happened many times). What will I do then?

Or, if I defeat the main troops, will the elementals disappear on their own? I don't think so. I think I killed everyone, but the elementals still remained. Or am I wrong?

Against a mage with elementals, a Warrior looks good because the stats are added to the number of elementals from the mage + the mage has no offense and armor.
Therefore, a warrior with elementals is a force, and a mage in the 2nd month of the game is easy prey.