This lyrics is based mainly on the "Dragonlance Chronicles"
Tuomas (the author) on this song:
"This is my personal tribute to fantasy, especially the closest to me; Tolkien & Dragonlance. These worlds have become a sort of inverted reality for me, where the story of "The Kinslayer"* can't become reality... Moreover, I don't believe in this thing called "destiny". We are the masters of our own wishes, beliefs and dreams. Whatever you desire enough, it can happen. Destiny is an excuse for those who don't have the strength to fulfil their wishes. Everything is possible. Even the impossible."
Now about the lyrics - if its not specified otherwise, then the word is taken from the Dragonlance:
Master - Raistlin Majere - arguably the main character of the Dragonlance Chronicles. He was a sickly, yet very intelligent boy who became the most powerful mage in the world of Dragonlance. He has been cursed with a sight showing how time affects all things.
Apprentice - Dalamar Argent - an elf exiled for using evil magic. Raistlin's apprentice
Heartborne - ? It could be a reference to the Tanis Half-Elven, the leader of the Heroes of the Lance (the "heart-borne" might suggest that he is a "born of love" between elf and human). Note, there were two versions of his conception: initially, indeed it was presumed that his mother was raped. The later one presented later says that his mother was indeed kidnapped but she fell in love with the brigand leader and refused to leave her human lover even after being "rescued" by her lawful husband. When her husband and lover kill each other, she returns home pregnant, saying that she was raped to protect herself and the unborn child.
7th Seeker - The Seekers were founded by men and women during the early days of the Age of Despair, who believed that the old gods had vanished for good, and were seeking for some new gods to worship.
Warrior! - Caramon Majere - Raistlin's twin brother. While Raistlin was physically weak and gloomy, Caramon was strong and light-hearted.
Disciple - Either again Dalamar, or more likely Crysania Tarinius, a human cleric from the church of Paladine. She is convinced that she can turn Raistlin from evil, instead, she falls in love with him.
In me the Wishmaster - the author of the lyrics, as someone who dreams about the fantasy realms
Elbereth - in LOTR: a Vala (goddess, or if you prefer one of the Ainur- the most powerful beings created by the one God Eru) responsible for creating stars above the world. She was the most beloved of the Ainurs and one that was the closest to humans and elves
Lorien - In LOTR: a name of the forest as well as the hidden within it elvish realm. It is also the name of the Vala of dreams.
A dreamy-eyed child staring into night
On a journey to storyteller’s mind
Whispers a wish speaks with the stars the words are silent in him
Distant sigh from a lonely heart
- While the general message here is that the author is like "dreaming child" reading the story, the "speaking with the stars" might refer to "Speaker with the stars", which is the official title of the royal firstborn child in Silvanost. During the "War of the Lance" this title belong to Gilthas Pathfinder (kudos to @AerusDar
“I’ll be with you soon, my Shalafi” - "Shalafi" has similar meaning like "sensei" or "master" in elvish. Used often by Dalamar when addressing Raistlin
Grey Havens my destiny - in The Lord of the Rings, the Grey Havens, known also as Mithlond, was an Elvish port city on the Gulf of Lune in the Elven realm of Lindon in Middle-earth. It was a place from where elves were sailing away to the Immortal Realms.
Silvara - In Dragonlance, a silver dragon, often in the Wild Elf form. She fell in love with another elf.
Starbreeze - Alhana Starbreeze, Silvanesti Elf, is first introduced in Dragons of Winter Night as the daughter of Speaker of the Stars Lorac Caladon.
Sla-Mori the one known only by Him
To august realms, the sorcery within
If you hear the call of arcane lore,
Your world shall rest on Earth no more - "Sla-Mori" means "secret shortcut", fairy road etc. In other words, this fragment means that "Him" (the storyteller, author of the book) can show you the magic in his stories that will take you away from this world.
A maiden elf calling with her cunning song
“Meet me at the Inn of Last Home”
Heartborne will find the way! - In Dragonlance: The Inn of the Last Home is a tavern in Solace that is famous for its wonderful food and ale, as well as being the meeting place of the Heroes of the Lance. It has seen several owners and a number of incarnations, but is still one of the coziest and most welcome inns for anyone wandering through Abanasinia.
Crusade for Your will - Not sure, it might be just a figure of speach ("your will be done") or it might reference the whole War of the Lance
A child, dreamfinder
The Apprentice becoming…
Master!… - It can be interpreted in many ways: Raistlin road from apprentice to mastery or the singer becoming storyteller
* "The Kinslayer" is another song from this album, which describes the story of the Columbine High School Massacre