Royal Drill

Royal Drill140 GRAM in game (≈14,000 CROWN at the presale rate), 70 GRAM in the presale

Adds +130 mining power. The power of every drill you own adds up, so a new drill does not replace the old one, it stacks on top.

Shards per hour from this drill = 130 × 300 × buildings × boosts × depth

At current competition that is about 842.75 CROWN per day, paying back in roughly 16.60 days.