A spell cast using harmonize will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way
Karbonala Warrior X EARTH Level 4 [ Warrior / Fusion ] ATK 1500 DEF 1200 "M-Warrior #1" + "M-Warrior #2" Darkfire Dragon X DARK Level 4 [ Dragon / Fusion ] ATK 1500 DEF 1250 "Firegrass" + "Petit Dragon" Musician King X LIGHT Level 5 [ Spellcaster / Fusion ] ATK 1750 DEF 1500 "Witch of the Black Forest" + "Lady of Faith" Fiend Skull Dragon X WIND Level 5 [ Dragon / FusionEffect ] ATK 2000 DEF 1200 "Cave Dragon" + "Lesser Fiend" (This card is always treated as an "Archfiend" card.) A Fusion Summon of this card can only be done with the above Fusion Material Monsters
Exile one of them face down and put the other on the bottom of that library
Against the current TCGplayer market price of $204.47, neither retailer has hit market value just yet, but Walmart has come close
These three monsters were able to Tribute themselves from the field to Special Summon one of the Sacred Beasts from various locations while ignoring their Summoning conditions, then they can banish themselves to add 1 other Sacred Beast or one of their support cards: In turn, these Sacred Beast support monsters can be easily accessed thanks to their main searchers "Dark Beckoning Beast" and "Opening of the Spirit Gates"
All because they activated a single card effect