These tips were submitted Evan Lieske, a tester on Orcs Must Die!

  • Brimstone will always hit Kobolds and Knolls (if it is not resetting), and it is the only trap that can kill orcs bearing a shield with one hit. Alternating rows of Brimstone and Tar (to slow the horde from running over the next row of Brimstone while already on fire) is my personal favorite.
  • Ice Amulet. Use it to save yourself if surrounded, stop an enemy near the rift, immobilize ogres for easy (or easier) headshots, tear through fliers, or use it to increase the damage of subsequent attacks (especially against ogres). It is worth bringing on every level.
  • Upgrade cautiously. Since there is not reset to upgrades using skulls, be certain to upgrade the better traps first. Spike traps, Push traps, and Boom Barrels would not be the best first. Instead go with Tar, Brimstone, and Decoys.
  • Tar. Cheap at only 300 coins, cheap to upgrade with skulls, never resets, slows enemies even more once upgraded with skulls, contributes to combinations, and can be used well in conjunction with many traps.
  • Barricades. They can make the difference between defeat and five-skulling, but be certain to not block every path to the rift. Close all but one path or snake the orcs along and you will find most levels simpler.
  • Shaman. If not distracted by Kobolds running by you or an ogre smashing your head, kill shaman first. They will resurrect individual orcs, ogres, and other shaman dead on the floor if they are not shattered by ice, incinerated by fire, or giblitized by a few select traps. Attempting to deal with four shaman resurrecting eachother is difficult without the Ice Amulet to keep the immobile and to shatter them.
  • Weavers. They are worth buying every single stage. Elemental weaver excels when traps are not enough to with a majority of the enemies or when two or more doors must be defended. Steel weaver supports traps and is essential if the trap setup emphasizes guardians or physics traps. Knowledge weaver can help in all situations with its various upgrades. Spending 1800 coins to earn double coins from spell kills and having those kills on an upgraded Coinforge (an extra 250%) will grant 52 coins instead of 15 per kill. Do this the first few waves when it is more likely to defeat an entire wave using only spells.
  • Leave some traps behind. In the beginning when options are few, use all that is available, but not far into the game it would be best to leave the Spike traps and Bladestaff behind. Everything can be good in the right circumstance, but those prime situations are not always common for every trap, weapon, or spell.
  • Check the enemy list before starting. If there are Forst ogres, consider bringing Flame Bracers (since Brimstone will not be enough). If there are Kobold Sappers, prepare to defend any Barricades set. Don’t pick or set traps not knowing what you will encounter.
  • Experiment. There are many ways to five skull every level on Nightmare and even more for War Mage. Do not limit yourself to the same trap setup each game. There is much repaly value in changing trap composition, and you will discover successful setups.
  • Accept a loss. There will be some levels that take more than one try to conquer. I needed about seven attempts to beat Rebirth on Warmage for the first time. Use any environmental traps or modify or even completely change your strategy.
  • Kobolds are fast, as you will quickly find. They are too fast to be hit by some traps, such as Spike traps and sometimes Arrow Walls and Pounders. Use Brimstone or Wall Grinders to kill them or Tar to slow them down for easy shooting. Keep away from the Sappers, and keep them away from your Barricades.
  • Chandeliers. They are effective on groups of enemies or even a single ogre, but it can be hard to time shooting them down when the enemies are below. I like to set a grid of Tar under them so that when the horde reaches the middle of my three rows I know they are directly under it.
  • Don’t just headshot. This is mostly for those who use the controller since you can hold the trigger to fire rapidly. Two great reasons to rapid fire are to remove the shields from many orcs and when you want to hit each enemy once before it dies to increase the combo on each of them by one.
  • Mushrooms. Try setting a mushroom under an ogre as it runs to convert it to your side. Doing so will leave you with less orcs chasing after the rift since many will engage the ogre, leaving you with the chance better defend the rift or to more easily defeat the wave. Converting ogres is excellent for offense and defense.
  • Decoys are a frequent rift saver. Use one to distract many enemies brielfy or a few enemies for a while. They are mostly useful against Orc Warriors and ogres, but are still worth upgrading immediately after unlocking.
  • Environmental traps. Keep watch for Boom Barrels that are given, acid and lava pots, chandeliers, and logs. Using them can pull you from defeat. The pots may even be used multiple times, so use them often.
  • Mix spells and traps. It would not be a good idea to bring only weapons and spells or only traps to a level unless you are looking for an added challenge. Typically, it is best to have two or three spells (Ice Amulet and Lightning Ring are my usual) and have the rest for traps, once you are able to have about six or more weapons or traps in a level. When you can only bring less it would be best to stick to one spell in most cases.
  • Trap compliments. Some traps are simply not very good alone, such as the Swinging Mace and Wall Grinder. But if Tar is set under the Mace and both Tar is set next to the Grinder (adjacent to it) and Barricades are next to the Tar (so that the Tar is between the Grinder and Barricade) to force the horde along the walls, you have a powerful setup that can work well on many levels.
  • Ogres. If not converting them with a Mushroom (since it is expensive), freezing them with the Ice Amulet then head-shotting the next simplest option. If the ogre is frost, consider the Flame Bracers (of course it is very effective) or use the Crossbow secondary to stun then headshot.