This legendary item improves with the person using it, improving their magic with the potency of skills trapped in the spirits of the cards. This item can turn any novice into a truly legendary spellcaster. This item is exceedingly rare, and there are only 1 known (complete) Decks of Skill-Cards in existence - the deck belongs to, and is held by, the creator. The Deck of Skill-Cards was created by a mythic mage of legend; Cameron the Clairvoyant. 

Deck of Skill Cards.  You gain access to a special mystical deck of tarot-type cards. Each has its own power. On each of your turns as a Bonus Action, you can draw from your Deck of Skill-Cards 1 card. The range of the abilities is sight, can be used on you and other creatures, and their effects last until the start of your next turn. You can make a number of draws equal to your level per long rest. To draw from the Deck of Skill-Cards - roll 1d20, and then roll 1d8 if you choose to, and consult the table below. You do not need to use the card when you 'draw' it, but you cannot hold the card for later usage - it must be used on your turn as part of your Bonus Action or as your Action (your choice). The DC of these card-spells is your spellcasting DC, or if you are not a spellcaster, the DC is 18. If the spell cast by the card requires concentration, you ignore that requirement, able to end the spell as the spell describes. You must recite the incantation to activate the card. 

1. Dollcraft - cast Conjure Elemental, bringing forth only an Earth Elemental or Fire Elemental, that is friendly only to you. "The words of Puppet Master Exthiel...O great Marionette of destruction... awaken to my call."
2. Necro Gate - cast Create Undead. "The words of Necromancer Gnelda...Wretched souls pounding at Hell's gate... it is I who hold the key."
3. Medusa Eye - cast Flesh to Stone. "The words of Luane the Condemned...O memories of sin faded by time... let it end with this conviction of stone."
4. Poison Breath - cast Cloudkill. "The words of Baldack the Avenger...The wanderer who fell to venomous fumes... his curse shall take hold."
5. Gravity Chaos - cast Gravity Sinkhole.  "The words of Aymia the Fallen...O angel deprived of light and wings... let thy misery cage mine enemy."
6. Item Break - cast Heat Metal as a 6th level spell. "The words of the Legendary Hawk...Swordsmanship honed in war... at thy strike even demon bones crumble."
7. Steal - selfcast Greater Invisibility. "The words of Saezar the Wind Demon...The shadow of the wind snatches all... even the treasure of the gods."
8. Bloody Claw - your critical range is expanded to 18-20 for the remainder of this combat encounter. "The words of Anon of the Red Moon...Crazed demon bathed in crimson moonlight... let fountains of blood rain from thy claws." 
9. Chariot - cast Haste, and also gain the effects of the spell; Longstrider. "The words of Gallad, the Steel Knight...O iron centaur trampling the battlefield... Thy spear pierces steel and flesh alike."
10. Shield Barrier - cast Wall of Force.  "The words of Hatti the Protector...Sage wielding the holy scepter of war... let thy light shield the weak."
11. Flame - cast Firestorm. "The words of Masende, the High Sorceress...O sorceress clad in the flames of Hell... let thy fiery incarnation bear its fangs."
12. Thunderbolt - cast Chain Lightning. "The words of Ruquion of the Heavens...He who strikes like lightning... Let thunder roar from thy fingers."
13. Blizzard - cast Cone of Cold. "The words of Ice Crusher Enreuke...O coffin of ice, sealing away anguish... invite death with thy bitter eulogy."
14. Banish - cast Banishment. "The words of San Asta Narev...O shepherd with earthly body and heavenly soul... Strike down evil with holy light."
15. Earthquake - cast Earthquake.  "The words of Doekes, Lord of Rage...O angry goliath, sentencing the earth... Shake Gaia with thy hammer of destruction."
16. Mind Change - cast Dominate Person. "The words of Gemini Aristella...Twin goddesses, each born with a single wing... in imperfection lies ever-changing hearts."
17. Revolution - cast Circle of Power. "The words of Nirvana, Goddess of Battle...O valkyrie of the doomed rebellion... In the depths of despair, sing us to victory."
18. Banshee's Cry - cast Synaptic Static. The words of Iona the Gravedigger...I summon thee, burier of the dead... Let thy shriek pierce the enemy's heart."
19. Mirage - cast Mirror Image on yourself and 4 other allies that you can see. "The words of Rubina the Dreamer...Whimsical faerie of the rainbow crystal... Let thy illusions become reality."
20. Rockfall - cast Wall of Stone. "The words of Ripfaike the Devilish...Mischievous demon plotting in solitude... Let boulders rain from the heavens."
21. Ace Guard - cast Heroism on all allied characters, disregard concentration requirements. "The words of Lion King Allemronde...O emperor, protector of many... Victory exists under thy flag alone."
22. Genocide - cast Meteor Swarm. "The words of Brongaa, Dragon of Purgatory...O ancient wyrm, enshrouded in a blazing aura... Thy flames shall unleash the fury of hell."
23. Sandstorm - cast Wall of Sand.  "The words of Lhasa, Guardian of the Desert...O protector of the endless sea of sand... Judge those who disturb order and stability."
24. Fortune - cast Divination. "The words of Vasuraha the Beholder...Blind seer, mute soothsayer... All of fate lies in thy cards."
25. Refreshment - cast Mass Healing Word. "The words of Cullin, Fairy of the Holy Spring...O spring of eternal purity... Bubble with the songs of the faeries."
26. Sanctuary - cast Sanctuary on yourself and 4 other allied creatures that you can see.  "The words of Laksimi the Half-Beast...O maiden of the sacred sanctuary... grant weary soldiers a moment of peace."
27. Crusade - cast Sunburst. "The words of Paltina the Creator...Divine empress loved by the phoenix Mulminams... Bring light to the darkness of chaos."
28. Mantrap - cast Wall of Thorns. "The words of Endomayla the Enchantress...Beauty that drove goddess mad with envy... Those who draw near shall fall into the abyss."