my ideal setup: upgrade archers, speartons, and giants to full. upgrade castle gold to max. upgrade miner's mining speed twice and bag capacity once. Didn't bother with swordsmen or mages.
Here is the specs of the tentacle enemies on the last mission, for those of you having troubles. These are observations from the hard difficulty. A tentacle can attack you during your turn if you try to move a trooper who is currently 2 spaces away from one, but any other action is okay. During the alien turn, the tentacles have longer range, but can only attack BEFORE they change position. The orange 100 HP tentacles have 3 range, the boss tentacle has 5 range. They can't see through walls, so use those 3 little walls in the middle of the map to hide behind after you damage it. If they have 2 troopers within their attack range, they will attack both of them. The boss tentacle makes 7 hexes of acid when it attacks, but only when it attacks on the alien turn. The magnet bomb effect can block the tentacles' line of sight, and it doesn't interfere with Pierce's bomb throwing. Very handy.
the dev so easily could have made the master of war a kred premium item with stuff to make the game too easy. It's nice to see some developers like Fly anvil showing restraint on these sorts of games.
 "Epic war")
 "Stick War")
 "Run 3")
 "Mechanical Commando 2")
 "SAS: Zombie Assault 4")
 "zombie horde")
 "The Great Siege"){kind=logo}
 "Fixation")
 "Mission in Space : the lost colony")
 "Bird-is-the-word!")
 "Decision:Medieval")
 "Book of Mages: The Dark Times")
 "13 Days After")
 "Epic Battle Fantasy 4")
 "Dark Cut"){kind=icon}
 "Trigger Knight")
 "Learn to Fly Idle")
 "3 eyes - Photos")
Sorry! I am French, and I translate with google translation ^ ^. Thank you for telling me the real term.