If you Tribute Set a high level Fiend-Type monster by Tributing this card, you CAN Special Summon another “Skull Knight #2” from your Deck and you do NOT have to reveal your Set monster to prove it is a Fiend-Type.
If you activate “Change of Heart” to control your opponent’s “Skull Knight #2” and Tribute it to Tribute Summon a Fiend-Type monster you can Special Summon a “Skull Knight #2” from your Deck. But if you activate “Soul Exchange” to Tribute a “Skull Knight #2” on your opponent’s side of the field, neither player can activate its effect.
If this card is used as a Tribute for a Special Summon, such as a Ritual Summon, the effect of this card is not activated.
If the Tribute Summon of a Fiend-Type monster is negated by “Solemn Judgment” or “Horn of Heaven”, the effect of “Skull Knight #2” will not activate.
If the opponent chains “Torrential Tribute” to the effect of “Skull Knight #2”, all monsters will be destroyed (including the Level 5 or higher Fiend-Type monster that was Tribute Summoned) and then “Skull Knight #2” will be Special Summoned from your Deck. If the opponent waits until the effect of “Skull Knight #2” resolves and another copy is Special Summoned, and then activates “Torrential Tribute” in response to that Summon, all the monsters will be destroyed.