The Colour of Magic [spoilers]
I'm not sure whether I've seen this sort of thing already discussed, but I won't uncroak an old thread if it was....
Findamancy seems to be associated with the color blue. The chained casters in 24:9 have blue aurae on their hands. Parson-summoning scroll as seen in 11:7-8 and 13:6, as well as all of the effects of that spell except the actual appearance of our protagonist in 17:9 (which was red) are blue. On second viewing, there is actually quite a lot of red in the build-up effects. But since the spell combines Findamancy and Summoning, the point is still valid.
In 18:1,4 we see that after his summoning, Parson has a red aura which quickly vanishes.
Healing magic has white or very light blue effects (22:1), as does the Arkenpliars' uncroaked-destroying abilities (22:8).
Portals are of several colors, as seen in 13:5. The one Wanda and Sizemore used to go from the Hippiemancers' glade to Gobwin Knob was green from both directions, though, so those colors could be arbitrary. Also, the Top Hat of Communication (10:9,11) has several different colors in its effects.
Now, the "Very hard way" in 30:13 came from a yellow-tan scroll and produces yellow effects. So does the Arkenhammer (4:10, 26), which is at least suspected of having charm- or command-related powers (causes dwagons to be loyal, 22:4).
Not sure I have an actual point, but as the strip progresses, I'm interested in watching this trend. It'll eventually help me generate crackpot theories during cliffhangings.