In MTG: Puzzle Quest, after playing for a while with a card in your deck you earn "Mastery" over that card. The app tells you this, with a +2 (that is, a symbol of colored mana matching the color of the card). What effect does this have over the card, the deck or your planeswalker?
From the official 1.5.8 Patch notes where this feature was added, there is a full explanation of what Color Mastery is/does:
We are adding a new major feature, called Color Mastery. In a nutshell, Color Mastery is a point system, per color. Color Mastery is accumulated by mastering cards.
● You accumulate points on each card in your deck at the end of every fight.
- Only cards in your deck get points, so you’ll want to mix it up to master as many cards as possible!
● Each card requires different amounts of points to be Mastered few for Commons, lots for Mythics!
● When you Master a card, you gain points in that card’s color in your Color Mastery chart.
- Colorless cards give you small amounts of points in every color
- Dualcolor cards give you points in both colors
When you enter an event (such as the Nodes of Power event), you will be set in a tier depending your Color Mastery, from Bronze to Gold.
- The event’s color determines which Mastery the game looks at for example, a Blue-only event would only consider Blue Color Mastery.
- Events that do not have color restrictions take your entire Color Mastery into account.
Each Tier in an event gives different rewards, and higher tiers give better rewards!