Cuff
I casted on 72 stitches on 2.5 mm needles in purple.
I knit 10 rows of 2x2 ribbing. I divided my stitches over 4 dpns.
Leg
I switched to size 2.75 mm needle and cut the purple yarn.
I knit one round of (k1 black, k1 orange).
I knit one round of (k1 orange, k1 black).
I then knit the pumpkin motif with black as the background and the pumpkin as the motif in orange.
I knit one round of (k1 black, k1 orange).
I knit one round of (k1 orange, k1 black).
I cut the orange thread and joined the white.
I knit the skull and crossbone motif with black as the background and the skull/crossbone motif in white.
I cut the white thread
I joined the orange thread.
I knit one round of (k1 black, k1 orange).
I knit one round of (k1 orange, k1 black).
I then knit the cat motif with orange as the background and the cat as the motif in black.
I knit one round of (k1 black, k1 orange).
I knit one round of (k1 orange, k1 black).
I cut the orange thread and knit one round in all black. Do not cut black.
Heel
I switched to 2.5 mm needles and with purple knit a fish lips kiss heel over needles 1 and 2. I cut the purple thread.
Foot
I switched to 2.75 mm needles and knit one round in black. I joined the white.
I knit one round of (k1 black, k1 white).
I knit one round of (k1 white, k1 black).
I then knit the ghost motif with black as the background and the ghost as the motif in white.
I knit one round of (k1 black, k1 white).
I knit one round of (k1 white, k1 black).
I cut the white thread and joined orange.
I then knit the witch motif with black as the background and the witch as the motif in orange. Cut the orange thread.
I knit one round of (k1 black, k1 white).
I knit one round of (k1 white, k1 black).
I then knit the bat motif with white as the background and the bat as the motif in black.
I knit one round of (k1 black, k1 white).
I knit one round of (k1 white, k1 black).
I cut the white thread.
I knit one round in black.
I cut the black thread.
Toe
I switched to 2.5 mm needles and knit 1 round in purple.
Work one decrease round:
N1: K1, SSK, K to end of needle.
N2: K to last 3 stitches, K2tog, K1
N3: K1, SSK, K to end of needle.
N4: K to last 3 stitches, K2tog, K1
Knit 3 rounds, then work a decrease round.
(Knit 2 rounds, then work a decrease round.) Twice
Knit 1 round.
Decrease until there are 9 stitches per needle, 36 stitches total.
Kitchener or graft your toe closed.
Weave in all your ends. This might take as long as it did to knit the pattern.
Final Thoughts
There are several things I would do differently.
First, I generally wear a 64 stitch sock and knit on 2.5 mm needles usually get 8 stitches/in. I was worried about the stranded knitting making the sock too tight. The scarf pattern calls for 72 stitches, so I kept that count AND increased to 2.75 mm needles. The socks have too much positive ease around, especially in the foot. If I could do this over, I would use 2.25 mm needles for cuff, heel, and toe, and 2.5 mm needles for the stranded colorwork sections on the leg and foot.
Second, the socks are too long. I think that I would leave out one of the motifs (probably bats) OR take out some of the smaller (K1 Black, K1 White) rounds OR rearrange the order of the motifs so that smaller ones occur on the foot and bigger ones on the leg.
I did not use all motifs from the scarf.