Introduction

Ritual good stuff decks benefits greatly from the release of the Impcantations. Now they're able to make use of monsters previously not  used outside their decks!

This is because Impcantation Inception can be used to summon ANY ritual monster, giving players easy ways to bring them out.
Let's check out some of the cool monsters to use with this in mind! Pre-Prep can also get a majority of them to your hand without worry.

Ethereal Royalties

Firstly, we have the two Shinobird Ritual monsters, bringing a strong start to the table! They certainly leave a big impact if their on summon effects go through, either clearing monsters or spells/traps and giving you a spirit monster to boot!
Amano-Iwato is the strongest target by far, locking the opponent out of monster effects. It doesn't return to the hand either since it wasn't Normal Summoned or flipped face-up. Players simply use it as material when it's their turn to use effects. You also get free tokens from their departure. 
The duo also happen to be wind monsters, a nice trait given the rising popularity of Barrier Statue of the Stormwinds as of late.
The Megalith card Och busts these two out during the opponent's turn, blowing them out completely if not interrupted! Phul helps greatly in this endeavor by netting a ton of free advantage and monsters to set this play up.
All in all, two powerful cards benefiting nicely from Inception and the Megalith package, arguably utilized more than within its own archetype!

The Dragon Queen

Saffira provides a lot of neat tools to the table to go alongside its ease of summoning, three gifts to work with that are all quite handy! She fills similar niches to Herald of Perfection (both being good Inception targets) while having some flexibility.
In some situations, you can continue to get card advantage every EP if she manages to stick around, which is definitely something you can do. In any case, it's a threat that the opponent is forced to deal with as if it sticks, it's going to keep plussing.
The most useful effect is to recycle a LIGHT monster in the GY, letting you reuse cards like Manju. It also lets you add back Benten as a follow-up. It can also get nifty power cards like Sauravis (which we'll get into later) and Artifact Lancea.
Drawing cards is always a good choice if you already have your pieces in hand, letting you dig through your deck and gather resources. If you have Archlord Kristya out paired with Saffira, this is where the discard effect can truly shine.
Being able to reduce the outs your opponent might have is a big factor! The hand rip can help in removing key threats like Imperm or Dark Ruler No More one way or another.

MAXing out the Chaos!

Inception can also tap into the powers of chaos and summon two high impact monsters to the field! Both work differently but are nice to keep in mind. 
Chaos Max Dragon puts the opponent in a fast ticking timer and has nice protection. Usually, most decks have ways to out this, but RGS can respond with the tools at their disposal to have other threats alongside it.
It also isn't meant to be the main focus, just an easy to bring out threat that can pile the hurt or clean up the game if needed.

Black Chaos, on the other hand, offers a two-fold effect. During your turn, you can use it and replicate the forbidden powers of Azathot to lock out from hand traps. This is huge as the opponent is left scrambling as you continue to play safely. 
Its more fiendish use comes in summoning it during the opponent's turn via the Megalith package to devastating results, potentially ending their entire turn!
This was shown in the recently concluded LCS V with Lundrity Velen successfully piloting Megalith to 2nd place (more so its own deck but still) and using Black Chaox Max's effect multiple times across the tournament to lock opponents out of their plays, thanks to Megalith Och's quick effect.
Most if not all decks are reliant on monster effects, so there's very little someone can do if met with this card. 
The effect to recur a spell also isn't terrible and acts as a nice bonus.

Advent of Doom

Gravity Dragon is the supreme clearer of Spells and Traps, allowing no responses from your opponent. They would also have to stop Inception or else it'd be too late to do anything.
Outside of that, it has beefy stats to help in finishing the opponent off after wiping their defensive options. Its continuous effect is also a persistent thorn to play against.
500 LP per effect may not seem much, but after taking a beating it becomes difficult to mount a comeback against the ritual player should they fail in winning that turn.
It's limited in what it can do, but the forgotten dragon is often the deadliest. If more backrow decks pop up, expect to see Gravity Dragon as a possible tech.

Arisen Emperor

Last but not least, we have Sauravis the Ancient and Ascended. This is the only Ritual monster on the list that you'll rarely be summoning, but if you do it, it's bound to leave a mark!
Sauravis is a strong and repeatable threat that has a nasty negation effect. If the opponent were to Special Summon a monster, you're able to return this card to the hand to negate and banish that card!
This is a unique distinction as it prevents a handful of monsters from getting floating effects off, as opposed if it were to destroy the negated cards instead. Since it returns itself to the hand, it's not very easy to prevent this effect from going off either! Therefore, making it quite hard to stop.
Once it's in the hand, it acts as a piece of protection that stops targeting effects on your monsters. This means you're able to secure key players like Archlord Kristya or Nekroz of Unicore. Not only that, but starters like the Impcantations also appreciate the help. 
Finally, it's key to know that you don't have to summon this card in order to use its effect in the hand, you can simply keep it in standby until the time is right.

Conclusion

RGS has come a long way from humble beginnings and will continue to evolve as time goes on. There's a lot of potential success to come and Diviner of the Heralds is just around the corner to boot.

The recent multiple victories of Megalith in the online scene also proves to be a good sign for Ritual strategies moving forward. It's only going to be up from here!