Why is Black Horn of Heaven not working 90% of the time?

[D. Seitaro]

"When your opponent special summons exactly 1 monster, destroy it" yeah right.

I play against opponents that special summon monsters from deck/graveyard/hand when this trap was placed last turn, and the game won't even ask me to activate it. What a total bs.

[edger]

You can only use that card against inherent summons (summons that don't start a chain, such as special summoning Cyber Dragon from the hand, or a Synchro/Link/Xyz summon)

[HeraldOfOpera]

This isn't the fault of Master Duel; Yugioh itself has dumb rules reasons why Black Horn of Heaven is way less useful than it sounds. As you've just discovered.

[dabestgamer]

When a card/effect is activated that includes Special Summoning a monster(s), you are not yet at the proper timing of "When a monster(s) would be Special Summoned". Now you start resolving the effect/Chain.

When the game state is at the timing of "When a monster(s) would be Summoned", there is an effect/Chain that still hasn't yet finished resolving. Neither player can activate cards/effects while an effect/Chain is still resolving. This is the correct time to activate Black Horn of Heaven, but the game rule prevents it because you must finish resolving the effect/Chain first.

Once the effect/Chain has finished resolving, the game state has moved past "when a monster(s) would be Summoned" to "when a monster(s) is Summoned", which is not the correct time to activate Black Horn of Heaven..

If there was an activated effect that was Special Summoning a monster(s), then it's working as intended. You cannot activate Black Horn of Heaven when such an effect is involved (unless it happens to state "immediately after this effect resolves, Special Summon...").

So again, the game rule that is stopping you from using Black Horn of Heaven is: You cannot activate cards/effects while another effect/Chain is still resolving.

[Zoie Shales]

Correct, It cannot be activated if the Special Summon is performed by the effect of another card
https://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=4&cid=6918&request_locale=ja

[Kreuz]

Can you give examples of what you could not negate?

Cause Black Horn of Heaven only goes after cards with inherent special summoning, like Cyber Dragon, Xzy, links, synchros.

It won't negate special summons from a card effect. That includes the monsters being special summoned through its OWN effect, like Nibiru.

https://ygoprodeck.com/important-yu-gi-oh-rulings-inherent-summons/

I admit, its a bit unintuitive.