Grim Grotto

The Grim Grotto is a mid-game prophecy trimming setup that yields a T-Spin Triple. Note that the order of the hang or trim are interchangeable.

Grim Grotto
The easiest way to remember is to look for the square shape. Make sure you use the right piece though. If you use the wrong S or Z, it will create an "empty" S or Z-Spin Triple instead.

Beware using the wrong piece!

Grim Triple Double
This is a greedier Grim Grotto (credits to XaeL):