A Shard Eruption is a recurring event in Sky: Children of the Light where a crystal shard falls into one of the game's five realms — Daylight Prairie, Hidden Forest, Valley of Triumph, Golden Wasteland or Vault of Knowledge — and cracks open the ground around it. Players who dive in and grab pieces of the shard before it disappears are rewarded with Wax or Ascended Candles. Sky Shard tracks exactly when, where and what kind of shard is erupting, so you don't have to guess or wait for the in-game warning sign at the realm gate.
There are two kinds of shard eruptions. A black shard is the regular eruption — it happens more often, gives Wax, and is safe to collect solo. A red shard is the strong eruption — rarer, pays out Ascended Candles instead, and drops a "wax monster" that chases you off the shard piece, so most players group up before going for it. Not every day has a shard eruption; each of the five schedule groups skips two fixed weekdays, which Sky Shard accounts for automatically.