>The Crimson King
>DARK Dragon / Synchro / Effect
>LV8 3000/2500
>1 Tuner + 1+ non-Tuner DARK monsters
>You can only use the 1st and 2nd effect of this card’s name each once per turn.
>(1) If this card is Synchro Summoned: You can add 1 card that mentions “Red Dragon Archfiend” from your Deck to your hand.
>(2) When your opponent activates a monster effect (Quick Effect): You can banish this card; Special Summon 1 “Red Dragon Archfiend” from your Extra Deck (this is treated as a Synchro Summon), and if you do, its current ATK becomes doubled, also it cannot be destroyed by your opponent’s card effects.

This lets you search basically any RDA card on synchro summon.
And note that >>725609815 allows you to chain block that effect from Ash.