Hybrid mana (also known as half-half mana) is a type of mana first introduced in Ravnica: City of Guilds and featured throughout the Ravnica   and Shadowmoor blocks.    Also, it was featured in Alara Reborn as an easier way to play three-colored cards, as was the theme of the block. It returned in Return to Ravnica and again in a much smaller role in Fate Reforged.
Each hybrid mana symbol represents a cost which can be paid with one of two colors. The hybrid mana symbol can be of any combination of two colors, or any color of mana and two generic mana. In textual terms hybrid mana symbols are represented as:
Shadowmoor introduced Monocolored Hybrid cards.
In the 2009 set Alara Reborn, hybrid symbols were featured alongside the "normal" mana symbols for the first time. For example, Jund Hackblade, was given the cost for the reason of it being a card with a converted mana cost of 2 that was needed to be tri-colored. The mana cost or is representative of the allied colors of red, black and green. Each is the others enemy, though they both are allied to the main color, red, or . All the hybrid cards in the set follow this patterning, thus all hybrid symbols were of enemy colors.
- Hybrid mana symbols appear only in costs, such as the mana cost in the upper right corner of a card or the cost to activate an activated ability.
- A card with hybrid mana symbols in its mana cost is each color that appears in its mana cost, regardless of what mana was spent to cast it. For example, the Deathcult Rogue is blue and black, even if you cast it with only blue mana.
- As you cast a spell or activate an activated ability with hybrid mana symbols in its cost, you choose which color of mana you will spend for each hybrid mana symbol. You do this at the same time you would choose modes or choose a value for an X in a mana cost. For example, you choose whether you'll cast Deathcult Rogue by paying , , or .
- Hybrid mana symbols were featured as rules card 3 of 6 in the Shadowmoor set and 2 of 8 in the Eventide set and 1 of 3 in the Alara Reborn set.
- The design for the hybrid mana symbols was chosen after careful consideration of other possibilities. 
- Three-color hybrid, or "tri-brid" is deemed too close to colorless, ugly and confusing. 
- Aaron Forsythe. (September 23, 2005.) "Ravnica: Review and Preview", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Aaron Forsythe. (December 23, 2005.) "Crossing the Streams", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (March 31, 2008.) "Shadowmoor than Meets The Eye, Part I", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (April 07, 2008.) "Shadowmoor than Meets The Eye, Part II", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Doug Beyer. (April 30, 2008.) "Hybrid Flavor", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Devin Low. (April 04, 2008.) "What's a "Monocolor Hybrid?"", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (September 22, 2005.) "Hybrid Mana Brainstorming", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (September 05, 2014.) "Did you ever consider tri-brid?", Blogatog, Tumblr.