TL:DR right up front I want a full fledge Shadow School where Spider teaches it in a separate world of his own after beating the game, allowing you to basically become a true Shadowmancer
Now for the long part sense about all you all bounced out after reading the TL:DR or left something like "No he wouldn't do that." He is a good guy now and we have a foot in the door for shadow spells, its not far off.
Unlocking the World This will require the full completion of the Emperya world, the defeat of the Storm/Aether Titan, and talking to Sybil about the mega NOTHING we gotta fear. Shadow will appear in your home next to the world door. Talk to him and he will inform you that he wants to train you in the true form of shadow, incase Sybil's warning is to be headed properly. The world door will become enchanted and will reveal only one world, Shaded Place (This can be any name really). You travel to this world and Spider and his children, Rat, Scorpion, and Bat will be waiting in a group, welcoming you to their home. This unlocks the world for you to return to at any time with a House Decoration.
In the World Spider will offer a quest, informing you that to truly master the shadow spells, you must choose one of his children to study under first. There is no order here and is done as you see fit. Rat will offer Auras, Enchants, and Minions, Scorpion will offer Damage, Blades, and Polymorphs/Shifts, Finally Bat will offer Shields, Buffs, and Fields.
Rat
Rat's questline will involve you using a starter set of shadow spells that he will hand you On him during a duel. He will do nothing but heal himself while you utilize Forced Aura, Shaded Sharpen, and Summon Nova. -Forced Aura will force an aura on the target, benefiting allies and hindering enemies. This aura will cause Allies to cast shadow pip needed spells without using shadow pips, lasting 2 turns, while enemies will see their spells costing more pips, 3 extra pips in fact, also lasting 2 turns. -Shaded Sharpen will cause your blade to apply a shadow blade in addition to the normal blade. -Summon Nova will cause a Tier 2 Dark Nova (The one that uses the pierce on you) on your opponent immediately and summon up a Tier 3 Dark Nova as a Minion. After clearing the fight, Rat will open up his training book and you will see a new tag for each spell, "Quests Completed for X" the X being the trainer. Rat will appear in 5 worlds and you will need to clear his 2 quests for him in each world, 10 all together, each quest cleared giving you a free training point and a TC of the spell you have just unlocked. Each quest will involve defeating a designated boss with a shadow damaging spell which will cause the boss to become enthralled. Take this boss on again in its new leveled up form for quest completion and some sweet Shadow Loot. Mooshu will be the example now.
Rat's Jade Oni Rat will task you to beat the Jade Oni with a shadow spell to entrall it and summon it back as a new enemy, the Dark Jade Oni. Defeat the Dark Jade Oni to complete this quest. Dark Jade Oni will be farmable, dropping powerful gear for your school with high shadow pip chance and a new effect, Shadow Cast.
Shadow Cast Shadow Cast works like a Maycast but abit differently. Upon use of a Pure Shadow Spell (Only using shadow pips), a Shadow spell is primed and will be added to your hand while a Shade of, lets use Jade oni for example, will appear behind you like a Dark Nova. This Dark Jade Oni will grow in power if you use the gifted card it adds to your hand. After 3 turns, It will do exactly what a Dark Shadow Spell does, dealing damage to all enemies, but it will then be summoned as a minion called Faded Remnant. This minion will always have the same deck but will be modeled after your own wizard.
Faded Remnant You can actively control what this minion uses and will have a deck comprised of what you have in your TC slots but they all do only Shadow Damage. Remnant will have 3/4s of your health (3000 if your health is 9000) and 1/3 of your stats (20% Damage if your Damage is 60%)
Do Rat's quests and claim all his spells to continue the Shadow Mastery questline.
Scorpion Scorpion's field of study for you will be pure offense. Same workings for Rat til you get to the quests. He will only appear in Upper Zigazag, Waterworks, and Tartarus. His quest is that you clear the Entire Dungeon using a deck of spells that he will grant you to prove your mastery over his powerful shadow spells. Your stats will not change so you will be using your Shadow Damage, Crit Chance, Accuracy, and Pierce. He will apply an effect to you as well, your pips will always be Shadow pips and can create Shadow Power Pips at a locked 20%. When you clear his quests and gain his spells, he will reward you with his Special Deck, The Dark Tome.
The Dark Tome Standard Deck stats for end game decks Fits 6 Copies of Normal School Cards Fits 10 Copies of Shadow School Cards Gain +1 Shadow Pip at the start of a battle Gain +1 Normal Pip at the start of a battle Gain +100 Health Gain the ability to gain Shadow Power Pips at +15% Chance Maycast Shift Scorpion Triangle Jewel Slot, automatically available.
Bat Finally onto Bat. This one works the same as his brothers. Time for his quests. He will only appear in the Arcanum and offer you a Quest chain to grant the Shadow Scholar more info on shadow spells by retrieving a few items, beating 2 bosses, and dueling her to let her practice some shadow spells. At the end of this, he will automatically grant you all of his spells and 3 items. A Wand, an Athame, and A ring.
Maycast Multicast (Guaranteed Cast if wand hit breaks a shield) 2 Square Slots 1 Triangle Slot Sublime Truth (Athame) +15% Damage +15% Pierce +10% Pip Chance 2 Square Slots
Decoder Ring (Ring) +15% Defense +25% Critical Block +10% Stun Block If Equipped, Defense stat is locked to 80% Universally and Flat Defense is locked at 150.
Equipping These items together will apply an infinite buff on you, going away when any one of them is unequipped. This buff causes your backlash to go Positive, causing it to heal you. Also Backlash will start at 0 at the start, going to a max of +30, healing you for 30% of MISSING health.
After getting all of the spells from Rat, Scorpion, and Bat, Spider will offer a duel to you, to test you on your new skills. No cheats, just a straight up fight. When you win, he will congratulate you and grant you 3 new shadow spells, Polymorph Rat, Polymorph Scorpion, and Polymorph Bat, each lasting 6 turns. He will state that there is 1 last Shadow Spell to learn before you become a master over shadow, Cataclysm (Explained later). To gain Cataclysm, you need to complete one final quest. Defeat Rat, Scorpion, Bat, and Spider. It is advised to gather friends for this as it will be a 4v1 otherwise. Good Luck there. When you beat them all, you will complete the quest and gain Cataclysm, the title Master of Shadows, and the Necklace Spider's Time Piece. Your shadow Pip bar will also expand to allow 7 shadow pips.
Cataclysm 14 Pips and 7 Shadow Pips, effects apply in order +45% Blade +50% Ward +25% Trap to all enemies Deal 2500 Damage to all enemies
Destroy all Charms, Wards, Blades, and Auras on ALL ACTIVE COMBATANTS (allies and enemies) This spell is meant to be used as a Finale Spell, used from position 4 to effect allies the least, and requires a LARGE build up.
Spider's Time Piece (Necklace) +20% Damage +5% Accuracy +35% Critical Chance +15% Pip Conservation Grants 4 Shadow Drains 1 Square 1 Triangle 1 Circle 1 Tear Shadow Drain - Deal 500 Drain and heal for half damage dealt
This is likely super broken/over tuned for Shadow Power as it is made for the mindset that you are giving up Normal Damage for Shadow Damage. You can likely see that the ring is super broken for Jades, but has a unique self balancing deal to keep Jades locked at 80% Resist universally in order to make sure that they don't become literally Immortal to even PVE content. The Finale spell, Cataclysm is balanced out that it will hurt you just as badly if you do not plan for it, destroying Charms, Wards, Traps, and Auras.
This Idea is likely to never come to reality, or, if it does, not as this is described, being super busted and what not. If you are reading this and have read all the way through, thank you for reading my labored efforts to make a suggestion that basically can read "Make Shadow A Whole School"
Accuracy
Damage