The All characters must die! tee design is a Game of Thrones tee for the fans of The Simpsons chalkboard gag.
As for the concept, the All characters must die! tee design is a mash up that plays on both Bart Simpson's punishment and Arya Stark's revenge list sleep mantra. The repetition theme is a common element for both characters. It is not the first time or the last time that these two franchises will be mashed up but this is the best and most obvious design to come from the combination so far.
This is done in The Simpsons drawing style and depicts Arya as the one writing on the chalkboard. The clothing is all Arya. But the face doesn't really look like her even if it is a Simpsonized version. As it just looks like Bart in a wig with eyelashes. But it does deliver the gag across. It is not worth taking away stars by nitpicking about which character's facial features should be dominate as that is just artistic preference.
Fans of either franchise could go for this shirt. But Game of Thrones fans would definitely be the main target here due to the list of names.
Now if only we can hear Danny Elfman play the Game of Thrones theme song.