Makai Senki Disgaea 2/Walkthrough/Episode 4
(4-1) Bloody Valley
Bring an ally with a 5+ panel attack range, to make things easier for yourself. Use this ally to destroy the red Geo Symbol across the river and that will negate the No Range Attacks effect covering the bridge. After that, use the bridge as a bottle-neck to group up enemies for your spellcasters and other multiple-target-hitters to rinse.
(4-2) Life Exchange
Once again, the enemies will not move until you approach them. If you're strong enough to take out the enemies quickly, you could choose to bombard them with group-hitting attacks as soon as you begin. If you would rather take on the battle slowly, then you should use a long range ally to destroy the moving "ATK +50%" Geo Symbol to prevent it from randomly giving your allies or your enemies an ATK boost every time it moves between the red and yellow panels on its little island.
(4-3) Red Waterfall
First thing's first, destroy the nearby "Enemy Lvl Up 10%" Geo Symbol ASAP. You do not want your enemies getting stronger every turn. Once that is dealt with, use Adell and a Sinner to form a wall on the bridge (with a Healer and an offensive magic user or two behind them as support) and let the Felynns come to you and get wrecked by your allies' counter hits and spells.
(4-4) Dragon's Mouth
First off, toss some allies over to the group of Geo Symbols and have them deal with the Thief guards. Next, throw the blue symbol onto the purple panel, the aqua symbol onto the green panel, and the green symbol onto the aqua panel in order to give yourself the advantage as you press on through the map. Once you have pushed past Axel's guards, get into his attack range to lure him off of the "Invincibility" panels that he is standing on. Keep him off those "Invincibility" panels and keep from getting pummeled by his counter attacks, and you'll have this battle won.