Invisible Decrease (invdec)
Perfect for amigurumi: reduce without gaps by working through front loops only.
Insert under the front loop of next stitch, then the front loop of the following stitch (2 front loops on hook).
Yarn over, pull up a loop through both front loops (2 loops on hook).
Yarn over, pull through both loops to finish the decrease.
Further reading: PlanetJune: Invisible decrease for amigurumi · Desert Blossom Crafts