Arknights: Guide to CB-EX7 Challenge, Mission, and Normal Mode

This guide will step through a strategy for clearing CB-EX7 that will work for the Challenge, Mission, and Normal Mode. For other Guides and event info, see the following pages:

Challenge Condition: 6 spaces on the map are no longer available for deployment.

Event Mission: S - The Apple Pie Dilemma - Clear CB-EX7 with 3 stars without having used the Portable Supply Station

• The Challenge Condition forbids deployment on the 6 grid block in the lower right.
• To achieve the Event Mission, we can't use the Supply Stations, which give Operators more Skill Points over time.
• The first obstacle of this map, as you'll see when it starts, is the Bulldozer that circles the outside.  It requires 3-block to stop, and has high offensive and defensive capabilities.  It starts in the lower left and will circle 4 times before exiting from the lower right.  2-block or lower Operators will simply be bypassed.  Blocking this guy too soon could mean trouble, so players will need to decide when (and if) to block him.
• The Rat King returns, and so does his now-familiar abilities.
  • The highest Max HP operator will be targeted by a heavy attack that hits all tiles in a horizontal and vertical line centered at the Operator (a + sign that extends to the edges of the map.
  • The lowest Max HP Operator will be targeted by an Arts-Damage-Over-Time effect that hits the Operator plus the 8 surrounding grids.
  • He has a high-HP shield that prevents Physical damage.
  • At 50% HP he will enrage and start hitting much harder.
• Otherwise it is the same types of enemies we've seen before: generally higher DEF than RES except for the Casters.

• 2 Skill-DP-Recovery Vanguard, V1,V2
• 4 Ranged Arts Damage Operators, AR1 - AR4.  The Slower Supporters attack ranges and Skills work pretty well for this map, especially against the Bulldozer, to both Slow him down and kill him. I highly recommend them if you have them.  Make sure one of these, AR1, has the lowest Max HP on the team.  Durin is an especially good survivability choice for AR1, as she has high innate Arts Evade, but her low damage would need to be compensated for by the other Operators.
• 1 Defender, D1, Make sure this is the unit that has the highest Max HP on the team.
• 2 Medics, M1 and M2.  M1 must be an AoE Medic, M2 an ST Medic.
• 1 Melee Operator, Me1, with at least 1 block.  Highly recommended that this Operator does Arts Damage, so an Arts Guard is ideal.
• Backup Operators: I'd recommend a Defender to stop the Bulldozer if needed, and 2-block melee replacements for our Vanguards, in case they die (or to replace them with stronger Operators)

Here is an example of the team I used:

Unit placement can be seen in the image below, and deployment order should be done exactly as presented.  Each Operator can be placed as soon as there is sufficient DP.

Deployment Order: 

1. V1: Texas - Skill-DP-Recovery Vanguard
2. AR1: Istina - Slower Supporter - This is our lowest max HP Operator that will be the target of the Rat King's AoE Arts Damage over time attack.  As mentioned earlier, Durin is an interesting defensive choice, though her low damage would have to be compensated for.
3. D1: Nearl - Healing Defender - This is our highest max HP Operator that will be the target of the high damage + shaped attack from the Rat King. Using a Healing Defender allowed me more time to deploy other Operators before the Medic.  If you use a Normal Defender, you might need to deploy the AoE Medic earlier.  
4. V2: Siege - Skill-DP-Recovery Vanguard
5. Me1: Indra - Brawler Guard (with S2)
6. M1 - Perfumer - AoE Medic
7. AR2 - Angelina - Slower Supporter
8. M2 - Silence - ST Medic
9. AR3 - Eyjafjalla - ST Caster

At this point we are at our Deploy Limit, and our formation should look something like this:

Once the 2 Greytail Leaders (the shielded dudes) that spawn from the top-middle (I6) exit are dead, and the middle is cleared of enemies, then:

• Retreat Me1 and Deploy AR4: Glaucus - Slower Supporter

The formation should now look like this:

This will be our formation for the remainder of the fight.  Here some things to note:

• The Vanguards can be replaced by 2-block Melee.
• If you can, try to time your Skills, especially multi-target Skills, for when the Bulldozer is passing within range.
• If you need to block the Bulldozer, do it on the final pass (after the 4th loop) on grid B3 with a Defender, but make sure this Defender has lower Max HP than our D1 or things will get messy.
• The Rat King will start hitting very hard at 50% HP.  be ready with any cooldowns to keep the blocker at B4 alive, and be ready to replace them if they die.  

Enjoy your OP!