Dungeons 2

Story related, can't be missed.

You'll get this once you beat the last mission The Battle For King's Ending.

The game is generally easy and gives you all the time in the world to sit in your dungeon upgrading and farming. The A.I will occasionally invade your dungeon but if you have any monsters or traps they are easily fended off, especially with spells to aid you. Almost every invading force will feature 1 or 2 halflings who are able to disarm your traps. If you see them and then kill them off with your fireball spell, the rest can be easily dispatched by your traps, especially if you're like me and like to lay out elaborate trap rooms for the unwitting heroes to wander into.

Even in the Overworld it should be easy enough especially if you have many upgraded units. The only tricky point in the campaign is with the final encounter but you will quickly get the trick and beat the final bosses.

The final encounter brings back the magic shield mechanic i.e when the shield is up, the boss is immune to all attacks. Kill the enemies that are casting the shield before going after the boss.

For maps with more than 1 entrance for enemies to flow from, find a way to re-route the passageways such that these entrances all link up and merge to a central area so that your traps can be maximised and enemy flows controlled.