Like most Magic: The Gathering cards, the value of Screeching Sliver depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Secret Lair Drop)
As always, the first mulligan is certainly something you can overcome in a dynamic longer game
The nastiest way to play the card is with wheel effects that make all players discard and draw
Galvantula Lightning HP100 Stage 1 Evolves from Joltik [L] Electrobullet: 50 damage
Their ability, Wash Out, allows you to move Energy from your Benched Water-type Pokemon to your Active Water-type Pokemon
With that in mind, we've gathered together a handful of tips to get things started, as well as recommendations for the best basic Pokmon and best Ex Pokmon to build your deck around