Fish engine maybe? It's hard finding 1 card engines with consistency cards, few bricks, and little conflicting with Necrovalley, but Toad is a card.
So, the list started with me thinking that Necrovalley is pretty good right now, we're in a format where two of the top decks are kind of in a league of their own, and Necrovalley is very disruptive to both of them, especially Drytron. It's also such an appealing engine to run, because you have so many copies of Necrovalley. Since it is good right now it has an edge over other field spell floodgates. However, Necrogoon is a little bit linear and relies a lot on Dragoon. Sure it usually puts up a Dragoon, but 1 negate + Necrovalley seems a little easy to out, provided people are prepared for a meta with Dragoon in it.
Dogmatika was the easy alternative engine to pair with it. Getting an interruption or three off of easy cards and searching backrow works well with the plan of Royal Tribute and traps, and there is no conflict with Necrovalley. The Fish part came in later in deckbuilding - I was basically looking for a 7 card engine, 3 starters 3 consistency cards and a brick, that could summon from the Extra Deck for Ecclesia, and worked under Necrovalley or at least could play around it being on the table. Invoked was the first thing I tested, but I found the engines conflicted too much to make Mechaba reliable. Destiny Hero would be appealing, save that Phoenix Enforcer can't revive itself under Necrovalley. I tried a few other small engines before remembering that Beautunaful Princess was a card and settled on the fish engine. It's actually pretty good, 1 card starter that gets you an omni-negate that pops with upside, and while it conflicts slightly it is really minor, and it was the perfect size, 3 consistency cards, 3 starters, and 1 brick. The brick is even not a brick sometimes.
The interruption suite has basically remained the same since inception, you need cards that don't conflict with Royal Tribute and are high impact.