Mossfire ValleyHow it works & interactions with other cards

How Mana Filtering Works

Mossfire Valley features a mana ability that requires two costs to activate: you must pay one generic mana of any type and tap the land. In return, the ability produces exactly one red mana and one green mana. Because this is a mana ability, it does not use the stack and cannot be responded to by players.

Resolution Step-by-Step

First, you must have at least one mana in your mana pool or another land ready to tap for mana to pay the activation cost. Second, you announce the activation and pay the {1} cost while tapping Mossfire Valley. Finally, {R} and {G} are added to your mana pool immediately. You cannot activate this ability if you don't have a way to pay the generic mana requirement.

Common Mistakes

The most frequent error is attempting to tap Mossfire Valley for mana on turn one when no other sources are available. Since it requires {1} to activate, it cannot provide mana to cast a spell unless you have already generated mana from another source. Additionally, remember that it provides both colors at once; you cannot choose to produce {R}{R} or {G}{G}.

When to Play It

This land is best played in decks with heavy color requirements in both red and green. It shines when you have plenty of basic lands or other non-filter lands to 'feed' its activation cost, ensuring you never get stuck with only generic mana.

Interaction examples

Fixing Your Colors

Command Tower

If you control a Command Tower and a Mossfire Valley, you can tap Command Tower to add one mana of any color (let's say Green). You then spend that one mana and tap Mossfire Valley to produce one Red and one Green mana. You have successfully turned one mana into two distinct colors for your spells.

Relying on Opponents

Exotic Orchard

If an opponent controls a land that produces Blue mana, you can tap Exotic Orchard for one Blue mana. Even though your deck might not use Blue, you can use that Blue mana to pay the {1} activation cost of Mossfire Valley, resulting in {R}{G} available for your Gruul spells.