In my opinion:
- Shien's Dojo, because this card makes Shien too easy to be summoned and spam the field
- Parasite Infestation, because this skill is f***ing annoying and makes Lava Golem become a 🔥
I can see them semi-limiting Dojo, Fuma, AND Enishi. Or maybe semi-limit two of them and limit the last one.
As for Lava Golem deck, limit both Lava Golem and Jade Insect Whistle. I'd add even more hits to ensure even the 🔥's variants also gets less consistent, but let's start with those two first.
For skill, I'd like to see Parasite Infestation being somehow limited to Insect decks.
Perhaps by making the skill not activate unless you have certain numbers of different Insect-Type monsters in your Deck, including at least 1 Level 5 or higher Insect.