In more conventional usage, the Heretic will always find viable targets
Sometimes there are Combo decks too, but most of the time we see ourselves confronted with a classic rock-paper-scissors metagame, where the slightly slower deck wins against the slightly faster deck, but the fastest deck beats the slowest
For me, the best decks score highly on the following axes: They added something new to the game, and just weren't another deck that played similar to many before and since
That said, playability doesnt matter a huge amount in this case
Representing a scaling down of power levels common in many cards from The Dark, it can still devastate a deck that relies on creatures like Llanowar Elves or Birds Of Paradise to generate extra mana, destroying them en masse if they don't attack
Beyond its breathtaking visuals, the cards scarcity is the stuff of legend (pull rates were astronomically low)