I'm helping my friend build a spellcaster deck but I feel that something is missing.....

Monsters: 20
Crusader of Endymion X3
Tuned Magician X3
Night's End Sorcerer X2
Effect Veiler
Jester Confeit
The Trickey X2
Cyber Dragon
Cybernetic Magician
Flamvell Magician
Breaker the Magical Warrior
Geomancer of the Ice Barrier
Summoner Monk
Magical Exemplar X2

Spells: 15
Gemini Spark X2
Monster Reborn
MST X2
Magical Dimension X2
Dark Hole
Supervise
Book of Moon X2
Secret Village of the Spellcasters X2
Miracle Synchro Fusion
Pot of Avarice

Traps: 5
Royal Decree X3
Mirror Force
Solemn Judgment

Extra Deck
Tempest Magician X2
Explosive Magician
Arcanite Magician X2
Stardust Dragon
Red Demon Dragon
Supreme Arcanite Magician
Black Rose Dragon Goyo Guardian
Ally of Justice Catastor

The Basic Strategy is to Limit you opponent's spell and trap usage while attacking with spellcasters, with other support cards
the mirror force and solemn judgment is in case he doesn't get his royal decrees right off the bat.