After summoning a Fiend, players permanently receive +2 gold after every wave.
A Fiend is a sinewy, sickly looking humanoid. Its two red eyes bulge out of their sockets, and savage, oversized teeth jut out of its lipless mouth. Its head is completely bald, and it has no eyebrows or ears.
Green spikes shaped like crooked teeth jut out of its back and elbows, and unruly green hair grows on its forearms and shins. At the end of its arms are not hands, but bone-white hooks, curved like fangs.
It stands on two clawed feet, but its posture is perpetually hunched over. When a Fiend runs, it uses its claws like ice axes to propel it forward. The result is awkward, but effective. Fiends are eerily fast predators from whom few can escape.