3 Tomb Keepers

Symbol Upgrade is a powerful feature that progressively converts low-value symbols on the reels into higher-value ones as the game proceeds. The core of this feature is not just a one-time symbol change, but a 'growth' structure where lower-tier symbols are permanently removed from the reels and replaced by higher-tier ones. This drastically increases the average expected payout of the reels towards the end of the round.

An Instant Prize Symbol is a special symbol whose role is to pay a set cash value or bet multiplier just by appearing on the reels. The core concept is that it provides a direct reward by its mere presence, without the need to form a winning line like regular symbols. It is often called a 'Coin' or 'Money Symbol' and serves as the most basic 'material' in various bonus features of modern slots.