If you hold the Shift button, the effect's sheet will be opened up for you to see and edit, after being applied.
This is useful if you want to quickly edit the effect - for example:
- Rename Mirror Image to "Effect: Mirror Image (3)",
- Rename Mummy Rot to "Effect: Mummy Rot (stage 1)"
- Change Steal Shadow's duration from Unlimited to 2 hours.
- Change Arsenic's image from the picture of a powder to a picture of deadly poison.