While Snow Mercy only gives those creatures counters, you can use Snow Mercy to tab down those creatures, and the fun part here comes with how you activated that ability because you have to tap, then untap, then tap, then untap, then tap Snow Mercy
This inconspicuous 0/1 will allow you to bring out even more threats because of the ease with which you can meet the requirements to cheat something into play
So why is Fallen Shinobi such an afterthought, then and now
that is, you could : but The Pokemon Company claims* to have solved the problem by placing 2 different types of code cards (cards that are basically useless for collectors and players, but can be redeemed in the online game) into booster packs
At its core, the card is a four-mana blue prejudice enchantment that says whenever an opponent casts a creature spell that doesnt share a color with a creature you control, counter that spell unless that player pays X, where X depends on the difference in color
The final card to make the cut is Scavenging Ooze which I deeply dislike as it seems to do too much and ruins quite a lot of different decks single handedly