There are 4 maps in this chapter:
14. A Mysterious Encounter
15. Escort Anata
16. Desert Mayhem
17. Protect the palace
Continue using 2 Shamans and all Warriors. Just move slow and take on one group of enemies at a time. When you are attacked by the lava lizards, quickly have the shaman protect, charge them with your Warriors, stun them when close enough and kill them; after the lizards die quickly stack your troops again and manually heal with the shamans.
On the stage where you need to be at two places at once, just leave the Shifter at the first one you visit. Make sure to remove the straggler from any hot keys you will be using with your main group, and then to go to the second place with just the Wari clan.
BOSS Worm: You are supposed to avoid when he charges, then hit him hard. You can just use the same head on strategy with nearby Shamans.