Hello hunters! This is a guide to all of the item combinations available on the server. If you see an item in the database that isn't on the drop table, odds are you will find it here. As a general rule, all items must be max grind in order to combine. Level requirements assume that the weapon is the strongest version of its type (e.g. Arms, Calibur, Striker).
If you notice anything wrong or missing, please let me know so I can update this. Thanks!
Credit: Orgodemirk, for reminding me that merges are a thing
Credit: Howitzer, for info on Orb of Illusions combinations
updated by @VEL(JP)
Weapons (bolded = Destiny Exclusive or Modified item)
Dark Flow = Sword series + Parasitic Gene "Flow" (Not server exclusive, but combo unlocked, buffed ATP and special attack doesn't lose the swing damage.) Requires LVL 140
Dark Meteor = Shot series + Parasitic Gene "Flow" (Not server exclusive, but combo unlocked, buffed ATP and N and H attack has 7 bullets instead of 5.) Requires LVL 140
Dark Bridge = Rod series + Parasitic Gene "Flow" (Not server exclusive, but it supports all RA techs and Grants, in addition Special attack can cast 3 of Grants lv22.) Requires LVL 130
Lavis Blade = Lavis Cannon + Syncesta Requires LVL 100
Double Cannon = Lavis Blade + Syncesta Requires LVL 100
Lavis Cannon = Double Cannon + Syncesta Requires LVL 100
Ultimate Double Cannon = Double Cannon + Dark Matter
Nightmare = Yamigarisu + Dark Matter
Hell Needle = Spread Needle + Dark Matter
Iron Faust = Panzer Faust + Photon Booster (Combo unlocked and All RA can equip it.)
Burning Visit = Flame Visit + Photon Booster
Snow Queen = Frozen Shooter + Photon Booster
Power Maser = Maser Beam + Photon Booster
Egg Blaster = Handgun series + Parts of Egg Blaster Requires LVL 90
Final Egg Blaster = Egg Blaster + Dr. Robotnik's Plan B
Arrest Needle = Spread Needle + Proof of Sonic Team
Summit Moon = Cane series + Magic Rock "Moola" Requires LVL 130
Magical Piece = Wand series + Magic Rock "Heart Key" Requires LVL 130
Sweetheart = Love Heart + Magic Rock "Heart Key" Requires LVL 131, female only
Rainbow Baton = Slicer series + Magic Stone "Iritista" Requires LVL 140
Black King Bar = Monkey King Bar + Blue-Black stone Requires LVL 100
Plantain Huge Fan = Fatsia + Magic Water Requires LVL 100
Plantain Fan = Plantain Leaf + Magic Water Requires LVL 100
Twinkle Star = Wand series + Star Amplifier Requires LVL 130
S-Berrill's Hands #1 = S-Berrill's Hands #0 + Berill Photon
Sange&Yasha = Sange + Yasha Requires LVL 100
Dancing Hitogata = Hitogata + Book of Hitogata Requires LVL 100
Guld Milla = Handgun:Guld + Handgun:Milla Requires LVL 100
Mille Marteaux = Heaven Punisher + Ophelie Seize Requires LVL 100
Jizai = Shouren + Guren
Arctic Faust = Iron Faust + Cryo Warhead Requires LVL 200
Celestial Fusion = Taste of Affection + Passion Haze or Passion Haze + Taste of Affection
Dual Bird = Master Raven + Last Swan
Striker of Chao = Branch of Paku Paku + Chao (MAG) Requires LVL 100
Armor/Shield (bolded = Destiny Exclusive or Modified item)
Behemoth Armor = Spirit Garment + Dark Matter
Brightness Circle = Spirit Garment + Star Amplifier Requires LVL 111
Aura Field = Spirit Garment + Magic Rock "Moola" Requires LVL152, no casts
Love Heart = Spirit Garment + Magic Rock "Heart Key" Requires LVL 131, female only
Safety Heart = Invisible Guard + Magic Rock "Heart Key" Requires LVL 123, female only
Parasite Wear:De Rol = Stink Frame + Parasitic Cell Type D Requires LVL 54, no casts
Parasite Wear:Nelgal = Parasite Wear:De Rol + Parasitic Cell Type D Requires LVL 66, no casts
Parasite Wear:Vajulla = Parasite Wear:Nelgal + Parasitic Cell Type D Requires LVL 89, no casts
Virus Armor:Lafuteria = Parasite Wear:Vajulla + Parasitic Cell Type D Requires LVL 156, no casts
Foie Merge = Red Barrier + Amplifer of Foie Requires LVL 6
Zonde Merge = Yellow Barrier + Amplifer of Zonde Requires LVL 6
Barta Merge = Blue Barrier + Amplifer of Barta Requires LVL 6
Gifoie Merge = Red Barrier + Amplifer of Gifoie Requires LVL 12
Gizonde Merge = Yellow Barrier + Amplifer of Gizonde Requires LVL 12
Gibarta Merge = Blue Barrier + Amplifer of Gibarta Requires LVL 12
Rafoie Merge = Red Barrier + Amplifer of Rafoie Requires LVL18
Razonde Merge = Yellow Barrier + Amplifer of Razonde Requires LVL 18
Rabarta Merge = Blue Barrier + Amplifer of Rabarta Requires LVL 18
Red Merge = Red Barrier + Amplifer of Red Requires LVL 24
Yellow Merge = Yellow Barrier + Amplifer of Yellow Requires LVL 24
Blue Merge = Blue Barrier + Amplifer of Blue Requires LVL24
Shifta Merge = Assist Barrier + Amplifer of Shifta Requires LVL 16
Deband Merge = Assist Barrier + Amplifer of Deband Requires LVL 16
Resta Merge = Recovery Barrier + Amplifer of Resta Requires LVL 11
Anti Merge = Recovery Barrier + Amplifer of Anti Requires LVL 13
Cosmetics (Destiny Server exclusive)
Orb of Illusions + Grave Digger = Nefarious Needle
Orb of Illusions + Behemoth Armor = Evil Aura
Orb of Illusions + Ultimate Double Cannon (on humar/hunewearl) = Lavis Storm
Orb of Illusions + Ultimate Double Cannon (on hucast/hucaseal) = Double Fury
Orb of Illusions + Cataclysm Shield = Hellfire Shield
Orb of Illusions + Three Seals = Profound Darkness
4th Anniversary Orb + Rathalos Great Sword = Terror Sawd (has bigger model than regular chain sawd)
4th Anniversary Orb + Christmas Spirit = Act of War (has alternative laser bullet)
4th Anniversary Orb + Storm Render = Twin Executioner (has alternative effect)
Blueprint: Astral Dragon + Final Egg Blaster = Astral Dragon
Mag (Destiny Server exclusive)
6th Anniversary Cell + Kama (lv50+) = Recon
Heart of Dark Chao + Non rare Mag (lv50+) = Dark Chao
Pandora's Box + Naga (lv50+) = Twin Wraith
Ideya Cell + Non rare Mag (lv50+) = NiGHTS
A New Friend + Sato = Twin Sato
Dragon Tear + Non rare Mag (lv50+) = Coelum
D-Photon Core + Kama (lv50+) = Gael Giel (not server exclusive, but buffed activation rate and movements.)