Hey guys, I’ve now won the 5 cave challenges, on my first playthrough. Here’s what I used for the big, bad level 5:
Hero: Diegraff the Red
Units: Goblins, Bombers, Taurus Warriors, Fire Succubus, Dragon Rider and Dwarf Engineer (all level 5).
Spells: Comet Shoot, Phoenix Strike and Hercule’s Strength (all level 5).
The strategy I employed was simple, but effective.
1) Wait until you have a fairly decent sized force in reserve, blasting the goblins and enemy commander with comets (just don’t use phoenix yet; you’ll set off the Invisible One-Shotter!) Hercule’s is handy too, but not really vital yet.
2) Once you have a fair force, get them to advance, clearing the way with comets (I tended to focus on the enemy bombers with my fiery friend).
3) Once they’re about to set off the Invisible Goblin, use phoenix. This will clear the path and set off the little bugger. He’ll kill a few soldiers from your vanguard, but nothing too serious. He’ll then go past them, rushing for your castle.
4) You then periodically send out small support forces (while your vanguard hammers their castle), who will intercept and delay the Invisible Goblin. At the same time, you need to be torching their reinforcements (weak, but annoying), chiefly with comet, but also with phoenix, as soon as their cooldown is done. With any luck, if you did all this, you should destroy their castle just before the Invisible Goblin reaches you.
5) Congratulations – You just won Cave 5.