Mancer Observatory: Proving Grounds 12 (Bastion Guide)

The Mancer Observatory with conductors in Bastion

Mancer Observatory is the proving grounds for the Calamity Cannon. It’s the final Proving Grounds challenge, and the hardest to complete in a single run.

Using your Cannon, you must defend 7 conductors from an invasion of 75 Gasfellas. Although they’re not that strong, they’re small and hard to hit with the Cannon.

That’s why it’s recommended that you settle for the 3rd prize on your first run, so you can fully upgrade the Cannon. Without the tier 5 upgrade, it’s almost impossible to reach the 1st rank.

Mancer Observatory
Rank Requirement Reward
1st All 7 Conductors remain “Calamity Rockets” Secret Skill
2nd 4 Conductors remain “Something Burnt” Upgrade Material
3rd 1 Conductor remains “Something Wrong” Upgrade Material


Get the Tracking Processor Upgrade ASAP / Bastion
Get the Tracking Processor Upgrade ASAP

The Cannon can kill all Gasfellas in one shot, so boosting its damage won’t be that useful.

Instead, you’ll want upgrades that improve its handling and effectiveness.

The best upgrade is at tier 5, but you can only get the material for it after a successful attempt at the Observatory. For that to happen, you’ll need all these upgrades first.

Calamity Cannon Upgrades
Tier Upgrade Name Effect
1 Supercharged Emitter Rockets cause knockback
2 Blast Generator +20% Blast radius
3 Speed Configuration +35% Reload speed
4 Incendiary Fuel Cell +20% Blast radius
5 Tracking Processor Rockets seek out foes

Note: You can get one “Something Wrong” material from Zulten’s Hollow — the same level where you got the Cannon. Two more can be bought in the Lost-and-Found. You can also win another from the Scrap Yard proving grounds.

Strategy + Tips

Tip #1: Shoot from in front of your target and not from a diagonal

Since the Gasfellas are always moving forward, it’ll be hard to hit them if you’re aiming from a diagonal.

Straight Shots Are Better Than Diagonals / Bastion
Straight Shots Are Better Than Diagonals

You’ll need to lead your shots, which can be difficult to pull off. The Gasfellas can also change course while you’re still aiming.

So you should always try to aim from in front of them if you can.

Tip #2: Don’t shoot Gasfellas that have gotten close to a conductor

Once a Gasfella reaches a conductor, they’ll start dismantling it. The danger there isn’t in their attack; it’s in getting rid of them.

Use Your Rolls to Kill Gasfellas Near a Conductor / Bastion
Use Your Rolls to Kill Gasfellas Near a Conductor

If this happens, shooting the Gasfellas will also destroy the conductors due to the Cannon’s AoE.

The solution to this is to not let it happen at all.

If a few Gasfellas do get past you, don’t shoot them. Keep blasting the ones that are still coming at you. When the only ones left are those near the conductors, kill them by rolling at them instead of shooting.

Tip #3: Once you’ve fully upgraded the Cannon, keep spamming rockets until you win

The tier 5 upgrade enables your rockets to home in on enemies. This eliminates the need for aiming.

The Rocket Curves as It Seeks Out Foes / Bastion
The Rocket Curves as It Seeks Out Foes

As long as you’re pointing at the Gasfellas’ general direction, you’ll always hit them.

So keep firing even if they’re beyond your line of sight.

You can also switch your upgrades at tiers 2 and 4 to the ones that improve your charge up speed. You’ll shoot faster with them in exchange for a smaller blast radius. And the blast radius won’t matter anymore because of the homing rockets.


Collecting the 2nd and 1st Prizes / Bastion
Collecting the 2nd and 1st Prizes

After the ordeal, you’ll get prizes based on the status of the conductors.

  • If there’s only one conductor left intact, you’ll get a Something Wrong for your Cannon.
  • If there’s at least four left intact, you’ll get a Something Burnt for the Galleon Mortar.
  • If you’ve saved all conductors, you’ll unlock the “Calamity Rockets” Secret Skill for the Cannon.
Secret Skill: Calamity Rockets (Calamity Cannon) / Bastion

Secret Skill: Calamity Rockets
(Calamity Cannon)

“Okay, now that’s just plain overkill. I mean, come on!”
—Rucks’s comment on the Calamity Rockets

You’ll unleash a rapid salvo of small rockets for 3–4 seconds. A couple of those rockets can obliterate most enemies.

So imagine how much damage you can do with a hundred of them shooting out of your Cannon. You can also redirect this flurry on anything that you want erased.

Louie Nelson Zafico

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As a frustrated otter who dreams of getting published, Louie instead wastes his life cuddling his cats. He spent his childhood playing Suikoden, grew up with Total War, and matured (somewhat) with EU4. He hopes to someday find a geopolitical JRPG with the 4X systems of a Paradox game.

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