Companion Creature
Companion creature refers to several types of creatures that are summoned to serve and fight alongside adventurers. Wizards, Sorcerers, Clerics, Empaths, and Rangers all have companions at their command, each with certain applications for combat, scouting, utility, or even just role-play. In general, there are four unofficial classifications of companion creatures.
Animal Familiar
Wizards are able to cast Call Familiar (920) to summon an animal to his or her side. Cast unaided, the spell calls out to the nearest appropriate animal in the region, resulting in an arbitrary familiar. If the wizard is attuned to a certain element, any wyrdling creatures that respond will be of the corresponding element. Once a wizard has found a fellow wizard to teach them the binding rune, they can use a binding rune to consistently choose a specific type of animal familiar. The familiar can act as a scout, allowing the caster to remotely view a location. It can also talk, in order to send messages to other players. Most notably, Familiar Gate (930) lets wizards use their familiars to allow transportation to or from a location via placement of the caster's familiar.
Spirit Servant
Clerics and Empaths are able to cast Spirit Servant (218) to summon a servant that will follow them. Although spirit servants cannot leave the caster, they are able to assist should their master become incapacitated. A spirit servant can hold an item in each hand; if its master is disarmed, the spirit will automatically pick the weapon up. If its master is killed, the spirit can preserve the body and send off a beacon to let other adventurers know where its master's body is located. Similar to wizard animal familiars, clerics or empaths can use a binding rune to consistently summon a specific spirit servant. Note that although the spell is based in the Major Spiritual sphere, the spirits summoned take after emotions and aspects of nature.
Ranger Companions
Rangers are able to cast Animal Companion (630) to befriend an animal permanently. Ranger pets can aid in combat by attacking creatures or defending the ranger. Feline and avian pets attack with slash damage, and canine and rodent pets attack with puncture damage. In addition, each animal type has a special attack. Moreover, avian pets can deliver messages to others, and both canine and feline pets can drag an object, such as a dead body.
Ambient Pets
Ambient pets are 'fluff' companions that have no mechanical benefit, and are simply a prop for role-play. They tend to reside on the person of the adventurer. Examples of fluff companions are: Bloodriven rats, grey squirrels, Dhu kittens, lizards, and shade skinks.