The Stream-Big
The Stream is the ninth level in Orcs Must Die! The Steam Trap is introduced here. The Hellbat is introduced as a new enemy.

Stage Description

It's a long, wide sinewy path surrounded by acid baths in which there are Doors: one at the far end of the map and one at the mid-point. Hellbats make their appearance from the skies at the north-east of the map. A portal allows you to cross the map from top to bottom, or northern Door to rift. There's an upper level seperate from the orc path from which you can station archers: you start out with two. You'll also find Boom Barrels scattered across the map.

Mob Waves (War Mage)

Enemies Encountered: Orc Warriors, Crossbow Orcs, Kobold Runners, Hellbats, Fire Babies and Ogres

1. Top gate: Orc Warriors x2

2. Top gate: Orc Warrior, Crossbow Orcs, Orc Warriors ;Window: Hellbats

3. Top gate: Kobold Runners, Orc Warriors, Kobold Runners

Go Break

4. Window: Hellbats, Hellbats; Midpoint gate: Orc Warriors

5. Top gate: Kobold Runners, Orc Warriors; Midpoint gate: Orc Warriors

6. Top gate: Crossbow Orcs; Midpoint gate: Warrior Orcs, Crossbow Orcs

Go Break

7. Top gate: Orc Warriors, Crossbow Orc ; Window: Hellbats 2x; Midpoint gate: Warrior Orcs, Crossbow Orcs

8. Top gate: Ogre, Kobold Runners; Midpoint gate: Warrior Orcs, Crossbow Orcs

9. Top gate: Orc Warriors, Hellbats, Crossbow Orcs ;Window; Hellbats x2; Midpoint gate: Ogre, Kobold Runners

Walkthrough (War Mage)

Pick Crossbow, Wind Belt, Spring Traps, Barricades, Tar Traps, Elf Archers and Arrow Walls

Start off by funneling the orcs where you want them: a barricade placed corner to corner with the first bend of the stream of acid alongside another next to it's top side and you've created a single square wide path for the mob. Place a Spring Trap at the opening, an Arrow Wall behind you and a Tar Pit in front of the Spring Trap. As you get past the first few waves, you can add more Barricades and Spring Traps. You're also in prime position to get the most out of your Wind Belt, pushing assembled orc mobs directly into the acid stream.

After the first break, the mob will crash through the mid-point gate: a couple of spring traps right past the roofed area will net some easy kills. Then again, this might be the best time to try out the Steam Traps: a couple of barricades to squeeze the mob path next to the wall and your steam traps will launch the mob two squares up into an Arrow Wall. The bonus is that the Arrow Wall will also be triggered by passing Hellbats. Continue adding archers and other assorted traps during the second break. Ogres won't be affected by either Spring Trap or Steam Trap and Kobold Runners can very well run past the trigger of your traps so you'll have to deal with them on your own.

Mob Waves (Nightmare)

Enemies Encountered: Shield Orcs, Crossbow Orcs, Kobold Runners, Gnoll Hunters, Hellbats, Fire Babies, Ogres and Armored Ogre (all flyers come out from the same window at the northeast of the map)

  1. Window: Hellbats & Fire Babies; Top Door: Shield Orcs

2.Window: Hellbats & Fire Babies x2 Top Door: Shield Orcs, Crossbow Orcs

3. Top Door: Kobold Runners, Shield Orcs

4. Window: Hellbats & Fire Babies x2; Both Doors: Shield Orcs

5. Top Door: Kobold Runners, Shield Orcs x2; Midpoint Door: Shield Orcs x2 , Armored Ogre

6. Window: Fire Babies x2; Top Door: Crossbow Orcs, Shield Orcs; Midpoint Door: Shield Orcs, Crossbow Orcs

7. Window: Hellbats; Top Door: Shield Orcs; Crossbow Orcs Midpoint Door: Crossbow Orcs

8. Top Door: Gnoll Hunters x3, Ogres x3; Kobold Runners; Midpoint Door: Shield Orcs, Crossbow Orcs

9. Window: Hellbats & Fire Babies x2; Top Door: Shield Orcs; Midpoint Door: Ogre, Kobold Runners

Walkthrough (Nightmare)

Starting with a build for the Steel Weaver enthusiast Pick Crossbow, Wind Belt, Ice Amulet, Lightning Ring, Steam Trap, Barricade, Arrow Wall, Brimstone, Wall Blades and Coin Forge

Get your Death Augmentator upgrade. Begin building what I call the money pit: go by the midpoint Door and build a coinforge across the center, then place three brimstones in front. Wait for your orcs there: that'll be your main killzone. You will be constantly harrassed by flying mobs: freeze hellbats first, then lightning bolts on the fire babies. Place a couple of arrow walls on the wall past the midgate about one and a half square high. Fit two brimstones touching the coinforge from the midpoint gate's side then add a wall blade along the side of the wall, blocking the path past the midpoint gate with barricades while lining the floor with steam traps.

You'll need the overcoiled springs upgrade by wave 5 so keep that in mind as you build your traps. Add more arrow walls over your previous row of arrow walls. Make the most out of your arrow walls and the Jagged steel upgrade: place them on any wall facing the general path of the mob, preceded by steam traps (such as at the start of the map). I wanted to try archers for this build but there's simply no room for them: arrow walls with jagged steel are great for slowing down mobs but have insufficient killing power for mobs exiting the midpoint gate, hence the wall blades. On the other hand, a clever arrangement of barricades and wall blades practically could make the arrow wall obsolete. Experiment.

The following is for those taking a different Weaver class. Pick Crossbow, Wind Belt, Ice Amulet, Lightning Ring, Tar Trap, Barricade, Grinder, Elf Archers, Coinforge, Mushroom Spores

Get either your Mana Conservation or Spell Magnification upgrades depending on the case, rush to the first ledge by the first Archer Guardian and add two more archers, then chase ahead of the main mob and plant a coin forge, killing the orcs for as much coin as possible. Add two more archers after wave 1 but take care; they'll be attacked on wave 2 by crossbow orcs so protect them with lightning bolts from afar.

For wave 3, arrange your killzone anywhere past the midpoint Door: barricades limiting the path to the width of a single square, filling the floor with tar traps, grinders at the end... The same spot past the midpoint Door in the first strategy works great because you're in full view of the archers over the second ledge. Save coins for wave 5 as that's where the Armored Ogre comes in: place spore mushrooms at the end of the path of tar pits and wind blast other orcs away so they don't interfere. Blow orcs away again so they don't hit your barricades trying to hit the Ogre. Keep an eye out for crossbow orcs and defend your armored ogre from flyers (he pulls a lot of attention and they'll eventually kill him through repeated fireballs): protect your ogre and he'll protect you.

Extra coin should be spent on two more grinders at each side of the first one and making sure you have twelve archers in all. When you hear the howl, wait for the gnoll hunters to come near then freeze nova and shatter with help from your archer friends. Try to convert as many ogres as you can; if not, freeze 'em.