Air-Strikes, prevent them by shooting down the bomber on its first pass when the plane is still tiny and flying in from the right side of the screen. I was able to shoot it down easily using the M60 Machinegun, you'll see black smoke that lets you know you're hitting it.
Trick to this game is understanding which items are the most useful. A full set of items that both add & reduce dmg will go a long way. Keep fighting extra battles to reset the shop so you can get the best dmg +/- items, doing so will maintain a battle advantage. Also make good use of your spell-interrupt, its often the difference between life and death.
I'll add to that psyn. Clerics in extreme mode, or any level on hardcore, are a boon to survivability. My most successful extreme, hardcore team is 3 clerics, 1 conjurer producing 2 bloodsprites. Note: at higher levels bloodsprites team heal to full. Deck your clerics out with full sets of runed armor for max pwr regen and nothing can defeat it, not with 5 team-healers and 4 that can resurrect.
Kensou8895, you can't run from a fight when you're in the middle of the desert loaded down with trade goods, unless of course you want to abandon everything you own to the robbers, at which point you might as well have died anyway, you'll be out of food & water. If you didn't , then you'd still be going as slow as you were to begin with, so they'd just catch you again two seconds later. So what are you asking for - an escape button that'll somehow makes enemies vanish off the map? Seems kinda unrealistic, these aren't random FF encounters, they're actual groups of enemies that if you're fast enough, you can completely avoid (as everyone does in late game when they have humvees and can move at 20kmh).
RyuKotetsu: Best stats 10phy, 10agi, 4acc, 1int. Great for early and late game. Early game you can run and gun with 15AP to start. Late game you have 100 hp for when they're lobbing RPGs at you and you need all the hit points you can get :) 4acc can be dealt with by using aimed shots in early fights and then equiping either of the two base 100 accuracy bonus sniper rifles (sold in Qubba/Fork Goks).
Also, despite it being counter-intuitive its best to have your highest lvl snipers using RPGs instead of Sniper Rifles. Reason being that the RPG7's base accuracy is very low (20) whereas the Sniper Rifle's base accuracy is extremely high (100). Hope this helps! :)
Robbers Base: If you manage to kill the first two guards extremely quickly, you don't have to fight the hordes of enemies that will pour out. If you're going to fight it out, you'll need your team decked out in 60pt military armor, M24 SWS Sniper Rifles, and RPG-7s
If your sniping skill is low, use aimed-shots and try to get your hands on a high base accuracy weapon like the M4 (70) or either of the two sniper rifles which have 100 base accuracy.