King Salmon prefer big flashy fly patterns and they are usually willing to take a bright fly on a dark day & a dark fly on a bright day. It is a good idea to carry a few different colors for various light conditions. The Fat Freddy works well for drifting or flipping with a floating line and a weighted leader. The Hareball Leech works well for casting & stripping with a sinking tip. The Stinger Prawn is an excellent choice for swinging & the Super Prawn is great for low water conditions, both are very popular patterns for Spey fishing.