Like most Pokmon cards, the value of Rillaboom V 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 (Fusion Strike)
4 Flynn Rider (His Own Biggest Fan) Discard The Cards, Gain The Lore
Three Steps Ahead A three mana MTG counterspell is distinctly unimpressive, but with a clone and a draw spell bolted on top, it gets a lot more promising
Turning all your creatures into mana dorks sets up some explosive turns, especially paired with greens big card draw spells like Last March of the Ents and Rishkar's Expertise
Bug Signal X SPELL Quick-Play Target 1 Insect Xyz Monster you control
Suddenly, all that discard, land destruction, and card drawing they've used has backfired, as they find themselves at a low life due to Necropotence, with two (or less) lands in play, no creatures, and no cards in hand