I wrote up the process for calling a familiar, Bascially the wizard goes out into the wild and anything within miles could be drawn to the wizard. It could be done in town, but anything that doesn't live in town might get killed looking for the wizard, and in town you are stuck with cat, dog, rat, mouse, snake or large spider. There is no guarantee of safety from animals not affected by the magic, ie the wolf that wonders into the circle might or might not be the animal drawn by the magic, and the wizard might be potential dinner. Even the attracted animal can deem the caster unfit and flee, or attack. The familiar can be any animal living or dead other then humanoid. (There is set up to prevent undead familiars, such as bless the imediate area, and don't use the magic near a graveyard.) Casting near a plane portal, could attract a beast from another plane, unless really powerful mage, I would assume the wizard would be attacked and killed for the attempt. The problems with larger familiars is housing them and keeping them safe when not at home. A cow for example, would be a welcomed meal for many poor family, and would not be welcome in a tavern or inn. Some examples might be: Frog, newt, large spider, squirrel(not jus any squirrel, a twained squirrel), song bird, bird of prey, vulture, owl, ferret, ground hog, badger, wolverine(not freindly to anyone else),Weasel, pig, fox, skunk(now that would be an unwelcomed friend.), wolf, coyote, wild dog, mountain lion, snake, lizard, deer, bison, rhino, elephant, how about giant insects? To give a few ideas of what might come to the calling.