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  Miscellaneous | spell catalysts
  Spell Catalysts
  This supplement introduces a new category of magic 
  items: spell catalysts. Spell catalysts can be harvested 
  from creatures or the land, each altering the effect of a 
  specific spell or spells. To use a spell catalyst, you must 
  have it on your person and you may use any number of 
  spell catalysts on a single spell. Typically, spell catalysts 
  are consumed when used. These new magical items are 
  presented in alphabetical order.
  Arcane Inverter
  Spell catalyst, rare
  At the heart of many golems and other constructs is a 
  polyhedral device that generates energy by creating a 
  constant feedback loop of arcane power. When you cast 
  the counterspell spell, you can choose to allow the spell 
  to consume this optional spell catalyst. When you do, if 
  you successfully countered the spell the target caster 
  takes force damage equal to 1d4 + 1d4 per spell slot 
  level expended casting the countered spell.
  Celestial Feather
  Spell catalyst, uncommon (+1d8), rare (+3d8), or very 
  rare (+7d8)
  These feathers can be harvested from the wings of 
  celestials or, less commonly, gifted by such beings. 
  When you cast the cure wounds spell, you can choose 
  to allow the spell to consume this optional spell 
  catalyst. When you do, the healing provided by the spell 
  increases by an amount determined by the rarity of 
  the spell catalyst. In addition, the target has advantage 
  on all ability checks, attack rolls, and saving throws it 
  makes until the end of its next turn.
  Dire Wolf Canine
  Spell catalyst, uncommon
  The sharpest teeth of the dire wolf can be extracted and 
  used as a powerful spell catalyst for hunters. When you 
  cast the hunter’s mark spell, you can choose to allow the 
  spell to consume this optional spell catalyst. When you 
  do, the spell lasts for its maximum duration and does 
  not require your concentration. 
  Dragon Egg
  Spell catalyst, uncommon
  Using the arcane potential within a dragon’s egg, 
  spellcasters can learn to take draconic shapes. When 
  you cast the polymorph spell, you can choose to allow 
  the spell to consume this optional spell catalyst. When 
  you do, the target of the spell turns into a dragon rather 
  than a beast. All other rules of the spell still apply.
  Dragon Heart
  Spell catalyst, rare (+2d6), very rare (+5d6), legendary 
  (+12d6)
  It comes as no surprise that the raw heart of a dragon 
  is a powerful arcane tool. When you cast the dragon’s 
  breath spell, you can choose to allow the spell to 
  consume this optional spell catalyst. When you do, the 
  target of the spell is resistant to the chosen damage 
  type of the spell for its duration. In addition, the 
  damage dealt by the breath weapon granted by the spell 
  increases by an amount determined by the rarity of the 
  spell catalyst.
  Dragon Scale
  Spell catalyst, uncommon
  Once liberated from their draconic owners, dragon 
  scales can be used to empower the defenses of others. 
  When you cast the mage armor spell, you can choose to 
  allow the spell to consume this optional spell catalyst. 
  When you do, for the duration of the spell the target 
  has resistance to nonmagical damage and a damage 
  type determined by the type of dragon the scale was 
  harvested from.
  Eye of Dire Newt
  Spell catalyst, uncommon
  Using the petrified eye of a dire newt, would-be hexers 
  make their hexes more dire. When you cast the hex 
  spell, you can choose to allow the spell to consume this 
  optional spell catalyst. When you do, the extra damage 
  granted by the spell changes from 1d6 to 1d12.
  Ground Gossamer Wings
  Spell catalyst, uncommon
  When ground into a fine dust, the gossamer wings of 
  the fae can enhance teleportation magic. When you cast 
  the misty step spell, you can choose to allow the spell to 
  consume this optional spell catalyst. When you do, the 
  spell duration becomes concentration, up to 1 minute. 
  While you are concentrating on the spell, you can use a 
  bonus action on each of your turns to teleport 30 feet to 
  an unoccupied space that you can see.
  Ironwood Root
  Spell catalyst, rare
  Treants of the ironwood genus produce roots that 
  can be used to infuse others with their strength and 
  regenerative capabilities. When you cast the barkskin 
  spell, you can choose to allow the spell to consume this 
  optional spell catalyst. When you do, the target’s AC 
  can’t be less than 18, regardless of what kind of armor 
  it is wearing. In addition, while the spell continues and 
  the target has 1 or more hit points, they regain 1d4 hit 
  points at the end of each of their turns.
  Mephit Core
  Spell catalyst, uncommon
  Mephits are tiny fragments of the paraelemental planes 
  come to life. When cracked open they have no internal 
  organs, but they do have a core that acts as a doorway 
  between the material plane and their home. When you 
  cast the find familiar spell, you can choose to allow the 
  spell to consume this optional spell component. When 
  you do, your familiar takes the form of a mephit of your 
  choice rather than an animal. 
  Dragon
  Damage Type
  Black
  Acid
  Blue
  Lightning
  Brass
  Fire
  Bronze
  Lightning
  Copper
  Acid
  Gold
  Fire
  Green
  Poison
  Red
  Fire
  Silver
  Cold
  White
  Cold
  
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  Miscellaneous | spell catalysts
  Miliese Prism
  Spell catalyst, common
  This transparent triangular, column-shaped crystal 
  fractures light into dozens of colors when held to the light. 
  When you cast the magic missile spell, you can choose to 
  allow the spell to consume this optional spell component. 
  When you do, the darts created by this spell deal a 
  damage type of your choosing instead of force damage. 
  Mimic’s Heart
  Spell catalyst, rare
  When a mimic dies, much of its shape-changing magic 
  remains in its heart. When you cast the disguise self 
  spell, you can choose to allow the spell to consume this 
  optional spell catalyst. When you do, the spell’s duration 
  becomes indefinite, ending only when you die or use an 
  action to end it.
  Monster and Spawn Reunion
  Spell catalyst, rare (+2) or very rare (+4)
  By replacing the normal material components, mundane 
  eggshell and snakeskin, with the eggshell and snakeskin 
  of a cockatrice, the bigby’s hand spell is greatly 
  enhanced. When you cast the bigby’s hand spell, you can 
  choose to allow the spell to consume this optional spell 
  catalyst. When you do, the summoned hand’s strength 
  increases by an amount determined by the rarity of the 
  spell catalyst.
  Monstrous Heart
  Spell catalyst, uncommon
  The heart of every monstrosity is an amalgamation of 
  multiple natural and unnatural creatures. When you 
  cast the alter self spell, you can choose to allow the spell 
  to consume this optional spell catalyst. When you do, 
  the duration becomes concentration, up to 24 hours and 
  you can choose two options instead of one.
  Phoenix Egg
  Spell catalyst, legendary
  A fertilized egg stolen from the legendary phoenix is 
  a powerful catalyst to restore the dead to life. When 
  you cast the raise dead spell, you can choose to allow 
  the spell to consume this optional spell catalyst. When 
  you do, the spell’s casting time becomes 1 action. In 
  addition, the creature returns to life with its maximum 
  hit points and has no penalty to attack rolls, saving 
  throws, or ability checks. When this spell catalyst is 
  consumed, it leaves behind a diamond worth 500 gp. 
  Pierced Pixie Eye
  Spell catalyst, common
  When a cold iron needle is run through the iris of a fairy, 
  the result is a powerful magical conduit. When you cast 
  the faerie fire spell, you can choose to allow the spell to 
  consume this optional spell catalyst. When you do, you 
  can choose any number of creatures within the spell’s 
  area of effect to automatically succeed on the Dexterity 
  saving throw.
  Poppystool
  Spell catalyst, uncommon
  This magical plant is a common poppy flower fruited 
  with small mushrooms as a result of a fungal infection. 
  When you cast the sleep spell, you can choose to allow 
  the spell to consume this optional spell catalyst. When 
  you do, you reroll each die whose result is a 1 or 2. You 
  must keep the second result, even if it is a 1 or a 2.
  Pupula Prism
  Spell catalyst, common
  This spherical translucent prism contains an opaque 
  black cone within. When turned in the light, a rainbow 
  of colors pour out from around the wide end of the 
  cone. When you cast the color spray spell, you can 
  choose to allow the spell to consume this optional spell 
  catalyst. When you do, choose any number of creatures 
  within the spell’s cone. Chosen creatures are immune 
  to the blinding effect of the spell and their hit points are 
  ignored when determining which creatures are affected 
  by the spell.
  Raven Tongue
  Spell catalyst, common
  Not all magical catalysts are especially difficult to come 
  across - this is simply the tongue cut from the throat 
  of a living raven. When you cast the speak with dead 
  spell, you can choose to allow the spell to consume this 
  optional spell catalyst. When you do, you and the corpse 
  can understand each others’ speech even if you don’t 
  share a language.
  Siselmi Crystal
  Spell catalyst, common
  This pyramid shaped crystal can be found in magic 
  enriched mines or, rarely, inside of earth elementals. 
  When you cast the magic missile spell, you can choose 
  to allow the spell to consume this optional spell catalyst. 
  When you do, the spell creates an additional dart.
  Spell Catalysts by
  Benjamin Huffman for http://sterlingvermin.com/
  Editing by Reed Dorsey
  Desktop for Publishing by Nathanaël Roux
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/5th Edition (5e)/3rd Party/Benjamin Huffman/Spell Catalysts.pdf