Hi, I recently just versed someone on YGOPRO that had a Stardust Dragon/Assault Mode on their field.
On my turn, I set down Solemn Warning, and attacked Stardust with my Bujingi Yamato (using Bujingi Crane in my hand to double the ATK of my Yamato by sending it to the graveyard).
This then sent the Stardust Dragon to the graveyard.
Before this, the opponent used Stardust Dragon/Assault Mode's effect to negate the effect of my Yamato (which is that I couldn't add a Bujin monster to my deck etc.), so therefore, he could special summon Stardust back onto his field from the graveyard on his next turn after it is destroyed.

I would like to know WHY I was not able to use Solemn Warning to stop this special summon. Am I not reading the card effect correctly? I'm still learning these cards, so if the answer is obvious, please forgive me!

Thankyou. 🙂
The Stardust dragons do not summon themselves during the next turn, but during the same turn's end phase. This was still the same turn Solemn Warning was set, so you could not chain it yet.
Ah, of course - that makes perfect sense! Thanks Snarky!