Japan didn't have shadowless cards, but these are essentially the equivalent
There are infinite combos that outright win you the game, like with Walking Ballista, but Heliod can be a centerpiece of devotion decks, +1/+1 counters, lifegain decks, and enchantment-based decks
Its also an artifact, so you have additional synergies with affinity, metalcraft, and so on
The design we landed on included dynamically updated ownership pips that were removed as cards were added to a deck, showing how many cards are still available to put into the deck
Typically the kinds of deck that want coverall counterspells also want to leave mana up to be reactive, having to tap five mana in your upkeep will make the turns following a Pact of Negation deeply uncomfortable until you have lots and lots of mana
"Shadowless" cards are from the next print run, which lacks the drop shadow behind the Pokmon's art box but doesn't have the 1st Edition stamp