TRK Headliner cards are mechanically identical to other TRK non Headliner card treatments
Insidious Roots fits into decks like Teval, the Balanced Scale, The Necrobloom basically anything that uses the graveyard for value
up to 1 of your opponent's Characters with a cost of 3 or less
At the beginning of your end step, create X 1/1 black Fungus creature tokens with This token cant block, where X is the number of times you descended this turn
A lot of balance and care goes into choosing the cost of a card, more than I can express here, but looking for similar effects on existing Magic cards can give you an idea of a fair costfor example, a ramp spell that puts two lands into play ought to cost 4 mana, per Explosive Vegetation
All Pokmon TCG Live in-game currency details and how to earn it Pokmon TCG Live Coins: How to use and earn them Coins can be earned through quests, leveling up, and other in-game interactions