Once it resolves, you add one red mana for each card in an opponents hand, that mana sticks around through phases until the end of the turn, and then Inspiring Refrain resuspends itself with another three time counters, letting you cast it again later
The usual play pattern for EI involves waiting until turn 3 or later to play a land from exile and choose a spell to place into your hand
It still sees extensive play elsewhere, though it's probably up to no good regardless of which format it shows up in
(2018-06-08) If multiple Arcane Artisans are creating tokens, each will exile only the ones it created
Psychologically, the Strength icon represents outward force
The set names seemingly refer to Mega Evolutions, which make a long-awaited return in Pokmon Legends: Z-A later this year, and this could be the first tie-in set with the game