Rounds 10-13 & the decrease stitch

New stitch alert! Meet the decrease (dec) stitch:

Round 10:	[4 sc, dec] x 6	(30)
Round 11:	30 sc	(30)
Round 12:	[3 sc, dec] x 6	(24)
Round 13:	[2 sc, dec] x 6	(18)