horn of heaven's effect: When a monster would be Summoned: Tribute 1 monster; negate the Summon, and if you do, destroy that monster.
princess curran can only be special summoned with trial of the princesses.
trial of the princesses effect: You can only equip this card to "White Magician Pikeru" or "Ebon Magician Curran". Increase the ATK of the equipped monster by 800 points. During a turn that the equipped monster destroyed a Level 5 or higher monster as a result of battle, by Tributing the equipped monster and this card, Special Summon from your hand or Deck: 1 "Princess Pikeru" if you Tributed "White Magician Pikeru", or 1 "Princess Curran" if you Tributed "Ebon Magician Curran".
AlephTTM said: I still don't understand what's going on.
Princess Curran was Special Summoned because the spell card Trial of the Princesses was equiped to the monster card Ebon Magician Curran, and that combination was used to destroy a level 5+ monster at the cost of those cards being destroyed. She is being unsummoned (destroyed) by the trap card Horn of Heaven.
tl;dr: Gaoo drew another girl being tortured (and snuff implications, oh my).
And to top it all off, technically you cannot use Horn of Heaven to prevent the summoning of Princess Curran, due to her special summoning is being done through the effects of Trial of the Princesses, lol.
RiderFan said: Are there any Yu-Gi-Oh cards that are simply "Destroy target creature".
quite a few, but they don't get used as often as you'd think. card's that negate and strangely cards that return cards back to the hand/deck are far more valuable then straight forward cards that simply destroy, though destroying cards is still useful.
Funny thing is, if that were the case (and it probably is), I don't think he's even using Horn of Heaven correctly due to ruling technicalities. Since it's a special summon-by-effect and not a natural special summon (like say Red-Eyes Darkness Metal Dragon's summon), which is what horn of heaven is supposed to be used against.