Hmmm Teleports are indeed powerfull for the player. Since i got caster only dynasties its actually pretty devastating with a half dozen of my children (each around 15-20 Mana).
But i did run into one problem. I can deal with one short front line or one choke point (in both Atack and Defense) but teleports are long-range stuff. I can also deploy a half dozen stacks in one single turn - maybe i can do that in lategame twice - after that i am normaly out of mana (or rather out of the amount i like to spend) for a couple of turns. To Date it happend to me twice that i got into a multifrontal war and more often the Ai used many smaller units (other players, bandits and monsters but mainly pioneers and heros) to flow around my stacks - right in the phase were i am out of mana.
The deploying of Megastacks is useless:
- if they are themselves to slow
- i cant teleport them often enough
If the Ai would consider these two things you would have some leverage against heavy teleporting players. Some ways to get around porting players i can think of right now solely ai vice are the following that may or may not build up on each other:
De- and Restack for attack and Defense
If a "Mega"-stack appears right of my troops i would do the following. Draw back and avoid fights as much as possible (thus flee) and then destack my own army into a number of smaller units. These 4 or 5 units (hero+trooper normally) can path now around the Megastack with different paths*. I might loose a certain number of troops but in the end the bigger number of my troops gets around the Megastack and restack to take the city or whatever.
The Megastack has two choices though: Destack itself or run for one of the smaller stacks. A good player might Destack to get all my smaller stacks which is on itself not that bad - it steals thought time. Enter: "the second row" - behind the first line of attackers or defenders could be a second row of smaller stacks that Restack with the fleeing troops to anhilate the parts of the Megastack.
The Ai should have Stacks stationed around the country-site (to kill the monsters and such). Normaly for wolves etc. small stacks are enough but if you have quite a number of them the AI could restack them into a fair army to counteract. Its expensive though to have mobile guards. Station troops in between Citys on the roads.
Hit and run strategy might be good on tac-map too. A small stack engages takes out one or two units (by archers and magic) and flees again. If you get some spiders into your guerilla team that web down the enemy its even better.
Following up the mobile guard idea : if you dont know where something will appear make sure you can control where it can appear and which conditions/paths it will find and can use. Keep empty but guarded zones between Citys such as Forrests or other slow movement zones which edges are guarded by faster units. Use "raise"-land and its counterpart to create artificial chokepoints (also works wonders for atacks). Do "burned earth" tactics on minor Setlements instead of defending them so the player cant create a bridgehead. Burned earth works also wonders for hit and run on the Game-map to shorten the supply of the player/enemy.
Scapegoats and Bait.
If the Ai "knows" (thus has seen a stack being teleported f.e.) that the player has 1 or two "mega"-stacks which he ports around and the Ai is attacking it can use scapegoat tactics to lure the Megastack(s) to somewhere else. The Ai could circumvent parts of the enemy territory and store a Megastack out of plain sigh. Then another unit does a Full Frontal Attack onto something. If the Player now ports his megastack its most likely bound because the caster lost lots of Mana. The Ais Megastack can now advance to take out some target or another. Or it could destack and take out resources and kill traders more sophistcated is:
Seek and destroy
As follow up use seek and destroy. Sort your targets into category for example make casters primary targets. If in a city is a price or princes advance with a small stack of archers (or own casters) and take him/her out. As soon they are dead flee from the battle. Take out resources with fast raiding troops like light cavalary thus destroy the supplylines and shorten the supply. Start with highclass resources like crystals or ventri andgold mines. Take into account distances if you want and avoid enemy troops if possible.
Take a city and move out again to get the next target. Avoid monsters and attack right after the player has taken care of them (thus might be lower on mana and injured)
* its Pathingwise a bit strange because you have to take into account not only the position of the enemy stack and a rough estimate of its range but also the other paths. Birdflocks react onto predators like this and there is 4th rule for boids for that behavior.
Btw. Portals are part of many modern fantasys. Many phantasy settings with multiple worlds use them like DnD, TDE, MTG (i have to say elemental reminds me to MTG in its beginning phyrexian war phase). Teleport was also in many phantasy games like Diablo(1,2,3) HoMM and so forth. In folklore you have also 7 mile boots, elves with secret paths and what not that essentially work like a fullblown portal.