In Slayers, Sylphiel is said to be the human of the group that is the best skilled when it comes to white magic and divination. White magic consists of spells that call upon the power of Ceiphied and offer peace, blessing, and healing, as well as protection. These spells are mainly performed by clerics. A cleric is a healer that has devoted his or her life to the holy service, using their powers in order to aid and protect others. Sylphiel is a cleric herself, more specifically a shrine maiden or priestess.
Because of this, her specialty is centered around healing spells such as Recovery and Resurrection and it makes her a greater caster of white magic than the others; Lina even once wished Sylphiel was with them in order to help heal the others when they faced Garv. Since she is a skilled healer, she can take care of many wounds at once compared to those who are less equipped in white magic. However, it does take a lot out of her when she performs high-level spells. Even though she brought Lina back from the brink of death using the Resurrection spell, it left her drained and she needed rest. This spell also doesn't seem to work against mazoku such as Phibrizzo for she was unable to bring back Amelia when she died.
Aside from healing, Sylphiel is useful with her skill in divination. She has a sixth sense intuition to pinpoint lost objects by sensing magic their owner marked them with. She's often asked to perform this skill when Lina and the others come to a stalemate. At one point in the series they come to a dead end in the ruins of Rezo's lab, so she used the scepter her father gave her as a medium to help her in scrying to find the right path. While her talents mainly reside to healing and divination, she has also been known to cast a very powerful protection spell. It's also the first spell she uses.
When it comes to shamanistic spells, Sylphiel greatly lacks in performance due to her lack of training and practice. For example, she has trouble when casting a Flare Arrow properly. The first time she tried it, it turned into a flare "carrot" and left much to be desired as an offensive spell. Though she has practiced with it, her levels are always inconsistent, usually too powerful or not enough depending on the situation. She can cast other shamanistic spells, but they aren't used as an offense to other living creatures and sometimes won't do as she would like them to. Another downside to her magic skills is that she becomes inept with them during "that time of the month" like all the other female magic users in Slayers.
Now because of her upbringing as a shrine maiden she has never had the need to cast any black magic spells, though she does have a vast amount of knowledge on them, specifically the Giga Slave. Sylphiel was the first to warn Lina about the consequences if she were to cast the spell incorrectly and even risked her life to stop Lina from using it. The only real black magic spell Sylphiel can cast successfully is the Dragon Slave, which is a highly destructive spell. She has never had the need to learn this spell because she has always lived a peaceful life, but after the experience with Kopii Rezo she decided to learn it as a way to protect herself when she travels with Lina and also to impress Gourry. The one time we see her use it was to help Lina defeat Phibrizzo combined with a Dragon Slave that Lina had cast. The plan would have been successful had Phibrizzo not escaped into the Astral Plane.
Sylphiel's arsenal of spells
This is a white magic spell, which creates a defensive shield and protects against most offensive attacks. This is the first spell we see Sylphiel cast and she uses it again in combination with the others' spells to protect them from Kopii Rezo's attack that destroyed Sairaag.
This is a spell of clairvoyance to find lost objects and allows the caster to extend the range of their senses. It needs to have a medium to focus upon in order to cast, such as a crystal ball or mirror and can only be used to find magical items which the caster owned, or items which the caster marked. Sylphiel used her scepter for this spell in order to find Rezo's legacy.
Flare Arrow (furea aroo)
A common attack spell that creates a flaming bow and arrow. Sylphiel leaves much to be desired with this spell for she does not put enough energy in it to attack others and puts too much when blasting holes through walls.
"Source of all power, crimson fire burning bright. FLARE ARROW!"
This spell creates a bridge of light, which will last as long as the caster concentrates on it. Sylphiel used this spell in order to retrieve the Bless Blade from the middle of a lake and required her to be barefoot. She fell into the water when Lina broke her concentration.
A different type of healing spell that takes longer because it absorbs energy from nearby life forms. Sylphiel used this spell to save Lina's life after Kopii Rezo attacked her.
A healing spell that heals the wounds of a target by maximizing the target's ability to regenerate. Sylphiel casts this spell to heal Flagoon at the end of the series to seal away Zanaffar.
"Oh, blessed and humble hand of God, life and breath of Mother Earth, come before me and show your great compassion and deliver us: RECOVERY!"
Dragon Slave (doragu sureibu)
One of the most powerful spells in black magic that calls forth the power of Ruby-Eye Shabranigdu. It's the strongest spell that humans can cast without need of a talisman and is able to decimate entire cities. Sylphiel can cast this perfectly and uses it with Lina's against Phibrizzo.
"Darkness from twilight, crimson from blood that flows; buried in the flow of time; in Thy great name, I pledge myself to darkness! Those who oppose us shall be destroyed by the power you and I possess! DRAGON SLAVE!!"