Your opponents wont be attacking or removing it from play in fear of what can come after, be it Omniscience, Cacophony Unleashed, Battle at the Helvault, or what have you
Remember, class enchantments stack, so you can play multiple copies and trigger their abilities simultaneously, but each card needs to be leveled up separately
For example, a creature that enters the battlefield with one +1/+1 counter on it won't receive an additional +1/+1 counter
Table of Contents show What Is Explorer
Notice how the black of the mana symbol and surrounding text are made of rosettes, and not black throughout
Historically, unfair decks abused mana better than fair decks whether that be Storm, Amulet Titan or Krark-Clan Ironworks