-- what is the [B] and the X?
the Red B and the white large X. i'm sure you have all seen it once or twice by now [B] is called solid_32x32, and is the sprite number 0 in the game's sprite database. when the sprite value is "undefined", it will most likely default there.
you will often see it when you call an attack that isn't defined, or the code is failing somewhere in the attack's file. X shows up when it can't find the sprite you tried to define.
for example, let's say you do sprite_get("magic") but you don't have a sprite named magic, then it becomes the X.