OPENERS · LESSON 3 OF 6
DT Cannon
AFTER THIS GUIDEYou can separate the scaffold, Double and Triple stages and identify what must remain after the first clear.
The first clear has a second job.
DT Cannon connects a T-spin Double to a T-spin Triple. The first construction is valuable because of the shape the Double leaves. If a placement produces a Double but destroys that continuation, it is not the intended chain.
Opening routes depend on piece order. Common starts use early L/S or J/L relationships, with alternative bases for other orders. The trainer presents compatible routes; it is safer to study those dependencies than to apply one memorised seven-piece order to every bag.
The initial T can be a structural piece rather than an attack. Do not judge progress by whether every T spins. Read the current stage: building a scaffold and executing its later attacks are different jobs.
After the Triple, inspect the surviving overhang. More spins, a Perfect Clear route or ordinary cleanup can follow, but none is automatic. In a pressured game, the time spent constructing the chain also matters.
Follow the stage boundary
Build the scaffold
The target below is the trainer’s first stage, before the Double. Identify the low supports and the central vertical I. The coloured T belongs to this scaffold; it is not evidence that a line has cleared.
Use the Double to reveal the Triple
In the trainer, follow the next stage and pause before its T. Predict which rows will disappear. After clearing, compare the exposed cavity with the next target.
Finish, then repair
Execute the Triple’s verified entry. Look at the remaining roof before celebrating the chain. Choose a plausible cleanup piece from NEXT or Hold.
Double → Triple. Colored cells show the first-stage reference, not placement order. Later bags, clears and alternative routes are not shown.
Play through one verified bag sequence
This is one supported reference route under the TETR.IO profile, not a prescription for every bag. Advance one locked piece at a time; each picture shows the board after any line clear. The practice mode may generate a different compatible sequence.
Start on an empty board. First bag: O → I → L → J → S → T → Z. Hold starts empty.
1. Place O. No line clear.
2. Place I. No line clear.
3. Place L. No line clear.
4. Place J. No line clear.
5. Place S. No line clear.
6. Place T. No line clear.
7. Place Z. No line clear.
8. Place Z. No line clear.
9. Place L. No line clear.
10. Place I. No line clear.
11. Place J. No line clear.
12. Place O. No line clear.
13. Place S. No line clear.
14. Place T. 2 rows cleared; the picture shows the result.
15. Place T. 3 rows cleared; the picture shows the result.
Common mistakes
Confusing DT practice with the DT Cannon opener
DT stacking builds on an evolving midgame board. The Openers selection teaches a predefined opening family. Choose the one you intend to practise.
Filling a cell needed by the second attack
A placement can improve the first target but ruin the continuation. Compare both stages before locking a structural piece.
Treating the post-Triple roof as someone else’s problem
It is the starting surface of your next decision. Include its repair in the plan.
TAKE IT TO THE BOARD
One chain, three explanations
- Open Openers and choose DT Cannon. Set Gravity Off.
- At the scaffold, the Double and the Triple, pause and state the purpose of the next T.
- Complete the route. At the finish, point to the leftover overhang and identify a candidate repair. Repeat with another attempt.
What counts as progress? You can explain what connects the two attacks rather than merely reproducing their end shapes.
Open practice ↗Opens the mode. Set Gravity and NEXT yourself; your current settings are kept.
Keep these terms nearby
NEXT IN THIS PATH
Perfect Clear Opener
Understand the base and the idea of a solution tree.
Read the next guide →Further reading
For setup variations and additional examples, see FOUR: DT Cannon. The practice task here is original to Stacking Lab.