CoT 5 is easy: monsters: goblins, dwarves, mermaid, fire succubus, centaur, and titan of choice (with least respawn time)
spells: healing wave, comet, freeze trap, lightning bolt, hercules, and athena protection.
The only monsters in this cave are goblins, bombers and a little uber goblin that u must not hit in the beginning! Send out your hero to delay the enemy and get your army spawned. After you have your titan, mass forward. Use hercules on ranged units and athena on goblins, dwarves and titan. Use ice, comet, and lightning for crowd control (revenge waves) heal when necessary
Note: all monsters should be level 5 and spells at least level 4