Named so as the pattern of ISZ resembles an unlit Beacon. This opening template existed beforehand in the Japanese Community as スピアード積み(Speerde Stacking).
After Kaidan this opener aims for stable 6-3.
General Shape
To rotate the I into position J, LO, or JOL tetrominos must be placed if not performing a wallkick. In games with symmetrical I rotations this cannot be done with J alone.
The First Bag has a 20.00% Perfect Clear chance, 3 solutions.
Main Stacking Method
This can be assembled 85.56% of all bags with one soft-drop, or 90.87% for two or more.
With mirror these values become 92.38% and 95.24% respectively.
Heart Variation
By alternating the heart shapes this covers 78.89% of all bags, resulting in favourable residue to freestyle 6-3.
Common ideas are to keep L or O in hold to fix height difference after a floating T-spin.
Other frequent stacks include the folllowing, the latter of which results in a 51.75% Perfect Clear chance with other Perfect Clear continuations that lead to a potential loop.
These Mechanical TSD setups are also possible with potential for Perfect Clears (see link):
- TSS Hamburger: This is best used when possible to hold I but is otherwise highly freestyle afterwards. Ideal stack and continuations shown.
It is possible to TST with a 90.44% Perfect Clear chance, 5 solutions or continue 6-3, note SZ pieces cannot always be placed as shown but the JO order can be swapped.
Mismatched Heart
It is also possible to stack like so 50.00% of the time when the LS heart shape comes in the wrong order. A mismatched OJ is possible, but entirely freestyle.
All Cover Variation
Covers 100% of bags, can be used independently or when the Heart variation fails.
- TSD: Look for which of L or S come first. If possible place S/Z as in diagram two after taking a T-spin, otherwise place Z rightmost always.
- STSD This path covers 100% of bags (note I spin will not work mirrored in SRS games) Created by ponix1.
For the first diagram, the I piece can be placed by soft dropping onto the edge of the Z piece, going left (right for mirrored), soft dropping, then rotating CCW (CW for mirrored). If the L piece has not been placed yet but the Z piece has, then a precise set of inputs can be made to prevent any waiting: soft drop onto the edge of the Z piece, go left, soft drop, go right into the small hole, rotate CCW (CW for mirrored), then go left.
For the second diagram, if the J and O pieces have already been place, the S piece can be placed by rotating CCW (CW for mirrored), soft dropping onto the ledge of the J piece, rotating CCW, soft dropping, rotating CCW, then going left.
With practice, these inputs can become second nature.
The I piece may need to be placed in the well or vertically to the side.
The first diagram is ideal and commonly buildable.
- O>L: For the sequence SJO use the last diagram, provided by metallicLurker, when unable to hold. The second template will suffice for 180 rotations.
Triple Double Upgrade
Upgrading into a TD Attack is possible but reduces stacking options.
Perfect Clear
Stacking for a Tetris works for both T placements. It also provides a Perfect Clear chance after 8 Lines meaning one can use DPC Setups afterwards to return to a fresh bag.
See Also
Interchangeable Shapes
