mtg bloomburrow showcase cards Valley Mightcaller (Showcase) [Bloomburrow] Bloomburrow (BLB) #305 Illustrated by Mariah Tekulve Magic The Most Valuable Cards From

That is why your opponent can counter your Arcane Signet before it enters the battlefield

Counters do not copy either

(2018-01-19) Some spells or abilities might cause a creature to explore multiple times in a row

If it does, be sure to snag several copies if you can, because it won't sit there for too long

Both sides of the card are viable thanks to the spell denial on your turn, meaning this is one of the few cards that really encourages the transformation aspect of getting it down early for the lower cost, then paying the higher cost to transform it when possible

That high value might not stick around forever though - a copy can still be worth thousands of dollars, but other promos have overtaken the tailor over time