Crowning Music of Awesome: You know something's going to die and that it will be epic when the Magun's theme starts up. Kumo's combat music has this effect, too.
Foe Yay: Kaze and Kumo certainly are obsessed with each other, considering how they always start fighting upon seeing one another.
Ho Yay: Implied when Kumo brings Kaze back to the Comodeen... Bridal style.
Memetic Mutation: "The soil charge triad to use on you has been decided!" followed by the name of the soil ingredients of a summon.
Related to the above, some people make up their own summons, often causing crossovers.
Most Annoying Sound: Whenever the Earl Tyrant speaks. At first he sounds rather humorous (especially in English!) but eventually he starts to grate on your nerves. In a strange way, it makes the viewer go Oh, Crap! when they see his true form...
Tear Jerker: Episodes 10, 13, and 18 all definitely count, as does episode 25 (and HOW).