Rikka are an underrated plant archetype and the only archetype from Secret Slayers that was overlooked, and hopefully this will change that.
The strategy works by firing off with Rikka Petal consistently from the first turn and during every turn you're able - DNA Surgery could make this easier given that the Extra Deck uses a lot of the Galaxy-Eyes and other Dragon Rank 8s because of how easily you can go into them via Snowdrop. Rikka Petal can fetch you Snowdrop or Mudan from the deck every turn and with just those two cards you can build the entire strategy. The idea is to flood the field via Snowdrop's effect of summoning two Rikka cards by tributing Petal, with Primula in hand as well, this becomes 3 and they can all be changed to Level 8, 4 or 6 via Snowdrop. This gives you access to all three of the deck's boss monsters (Teardrop, Strenna and Kanzashi respectively, or even Number 87: Queen of the Night!) and can lead to systematically removing your opponent's monsters by using Rikka Flurries off of Mudan's fetch effect. Once Snowdrop hits the GY (you ideally want to detach her from any Xyz monster first), simply use Rikka Tranquility to bring her back and circumvent her locking effect. With a recycled Snowdrop, the Galaxy-Eyes and Dragon Xyz portion of the Extra Deck becomes available to use and finish off your opponent with overwhelming prejudice.
By using either Galaxy-Eyes Photon Dragon, or the small portion of Blue-Eyes support as well, you want to link into Galaxy Satellite Dragon for the final combo (if you can get Galaxy-Eyes Solflare Dragon out too, that's a bonus) in cooperation with Number 107: Galaxy-Eyes Tachyon Dragon. Combine these dragons' effects together and Tachyon Dragon will soar to 10,700 attack points, attacking your opponent twice, and negating their board for that Battle Phase. At that point, the game is over.
Constantly tributing your Rikka and plant monsters will keep Rikka Flurries firing off, which forces your opponent to tribute their own monsters. And with a plant material on any of your Teardrops, her effect becomes a quickie and will tribute yet more monsters for your opponent. A cheeky tech is using Strenna in rapid play and tributing her to fire off Flurries and gain a fresh Teardrop and using her effect too. With Kanzashi on the field with them, you don't even have to tribute cards you don't want.
The real gem in this deck, is Rikka Petal - providing you control only plants or no monsters at all, she comes back to the field during your opponent's End Phase. And this can be extremely annoying for them to try and deal with. Even if they banish one of her, you still have two copies, and even Lonefire Blossom to fetch her again and again. Constantly recycling Snowdrop and Mudan with Tranquility can recycle so much of your GY, so don't worry about your deck thinning, this is what you want. Combining DNA Surgery, or possibly even two copies of it can help you keep Flurries on the field, as well as dealing with the Zombie World Deck at Rogue currently by making your Rikkas plant monsters even after they've played Zombie World. In addition, Rikka isn't effected much by Buster Blader and his deck given that you can force them to tribute around the Swordsman/Dragon lock combo and then use Teardrop to get rid of the other one once you're out of it.
In combination with the Rank 8 package, this deck just becomes mean with a consistent method of summoning monster after monster with 3000+ attack points or equally annoying effects.
420
390
540
300
