Merging and splitting stones

×5 → Common → Rare — 80% success

×5 → Rare → Epic — 75% success

×5 → Epic → Legendary — 65% success

×5 → Legendary → Mystic — 60% success

Put in 5 stones of one tier — one merge per tap. Fail and all 5 are gone. Mystic stones are the top tier and cannot be merged.

One stone becomes 3 of the tier below — always works. Common stones cannot be split.

Merging takes 5 and splitting gives back 3 — split when you need lower stones, not for profit.