Now don't get to existed, this small spell is more for dark juniors, who are only starting off in the field of dark arts.

With this spell you may summon Thestral easily, you can use this to your advantage if you need a ride, be it to escape or otherwise.

Thestral while not necessary evil creatures or dark, are often clouded in a negative light as it is a known fact that you can only see them if you have experienced death.  Little is known about these mysterious creatures other then that they are meat eaters, carnivores if you were. In appearance they are a breed of winged horse with a skeletal body, face with reptilian features, and wide leathery wings that resemble a bat's remarkably well. They are very rare, and are even considered to be dangerous by the Ministry of Magic. Thestrals are, undeservedly, known as omens of misfortune and aggression by many wizards, this could be due to either their appearance or because of their rep as a bad omen. 

Thestrals can be domesticated and mounted, so they are used as an alternative to brooms, apparition and other methods of transportation. Once trained, they are very diligent and will quickly carry their owners wherever they wish to go, so you can see how they can be of use to a wizard dark or light. However, travel by Thestral is technically illegal, as it is a breach of the International Statute of Wizarding Secrecy and Due to their classification as XXXX, only experienced wizards should try to handle Thestrals. Breeding as well as owning these beautiful beasts may be discouraged or even illegal without Ministry consent; in fact, wizards that live in areas not protected against Muggles are forced by law to perform Disillusionment Charms on their Thestrals regularly. (but hay, what do we care right? We're dark wizards! Haha.) 

Thestral's are loyal creatures, able to discern a friend from an enemy. Thestrals would forcefully attack anyone or anything they see as a threat and, in the unusual case of domesticated Thestrals, any enemy of its owners. They do seem to be attracted to the smell of blood, so if your a lover of wars or battles you can surly rely on the Thestral to lead the way. These creatures are invisibility  to everyone who hasn't seen death and let me tell you there aren't many people who have so this is also very useful for your evil doings.

The Thestral may not seem like much but these intelligent beautifully dark creatures can be a wizards best friend if you are smart enough and gain their trust!  Now, on to how to actually summon them. For this spell you will have to have not only witnessed death and accepted it but have had experience with Thestral's as well. 

We are assuming that you have all the requirements and wish to summon one in a means of escape or the like. You will have to start of by dipping the tip of your wand in some blood, any type of blood will do. (It may be handy to carry a phial around with you with a little in so that you always have some on hand.) Move your wand in the shape of a horse shoe and back again saying with clear pronunciation, the incantation 'Letum Equus'. ( Let-U-m Eq-U-us.) 

No matter where you are your Threstal friend will find you, and there you have it, easy as freshly made pumpkin pie! This spell is called the summoning of the wings of death. ( The Summoning for short.) There will be no warnings for this spell other then the importance of gaining their trust first and the dealing of dark magic, coninue at your own risk.