The first main phase in each turn is called the precombat main phase. See rule 305, “Main Phase.”
Effects that prevent something from happening replace it with “do nothing.” (See rule 419, “Replacement and Prevention Effects.”) A prevention effect must be active before the event it’s intended to prevent.
Effects that prevent a specific amount of damage act as “shields” and stay active until that amount of damage has been prevented or the turn ends. The damage doesn’t have to be dealt by a single source or all at once.
Effects that prevent the next damage from a specific source apply the next time that source would deal damage, regardless of the amount. These effects expire when the turn ends. See rule 419.8, “Sources of Damage.”
The player who has the option to play a spell or ability at any given time has priority. See rule 408, “Timing of Spells and Abilities.”
Each time a spell, an ability (other than a mana ability), or combat damage resolves, and at the beginning of most phases and steps, the active player receives priority. If a player has priority when he or she plays a spell, ability, or land, or takes a special action, he or she receives priority afterward. When a player passes in a two-player game, his or her opponent receives priority.
If all players pass in succession, the spell, ability, or combat damage on top of the stack resolves or, if the stack is empty, the phase or step ends.
Each time a player would get priority, all applicable state-based effects resolve first as a single event (see rule 420). Then, if any new state-based effects have been generated, they resolve as a single event. This process repeats until no more applicable state-based effects are generated. Then triggered abilities are added to the stack (see rule 410). These steps repeat in order until no further state-based effects or triggered abilities are generated.
In the Two-Headed Giant multiplayer variant, teams rather than individual players have priority. See rule 606, “Two-Headed Giant Variant.”
Protection is a static ability, written “Protection from [quality].” See rule 502.7, “Protection.”
A permanent with protection can’t be targeted by spells with the stated quality and can’t be targeted by abilities from a source with the stated quality.
A permanent with protection can’t be enchanted by Auras that have the stated quality. Such Auras attached to the permanent with protection will be put into their owners’ graveyards as a state-based effect. (See rule 420, “State-Based Effects.”)
A permanent with protection can’t be equipped by Equipment that has the stated quality. Such Equipment becomes unattached from that permanent, but remains in play. (See rule 420, “State-Based Effects.”)
Any damage that would be dealt to a permanent with protection from sources having that quality is prevented.
If a creature with protection attacks, it can’t be blocked by creatures that have the stated quality.
Provoke is a triggered ability. “Provoke” means “Whenever this creature attacks, you may choose to have target creature defending player controls block this creature this combat if able. If you do, untap that creature.” See rule 502.29, “Provoke.”
Some information within a Magic game is known by all players. For example, permanents in play, spells and abilities on the stack, and cards in graveyards are all public information. The number of cards in players’ libraries and hands is also public information, even though contents of those libraries and hands are hidden information. See also Hidden Information.
If an effect instructs a player to put an object into play, that object is not considered “played.”
Rampage is a triggered ability. “Rampage N” means “When this creature becomes blocked, it gets +N/+N until end of turn for each creature blocking it beyond the first.” See rule 502.12, “Rampage.”
If a spell, ability, or effect requires a player to choose something at random, that player can use any method of making a random choice (rolling dice, flipping a coin, and so on). The outcome must be truly random.
Recover is a triggered ability that functions only while the card with recover is in a player’s graveyard. “Recover [cost]” means “When a creature is put into your graveyard from play, you may pay [cost]. If you do, return this card from your graveyard to your hand. Otherwise, remove this card from the game.” See rule 502.55, “Recover.”
Some older cards were printed with the term “redirect” to describe the act of dealing damage to a different player or creature than originally specified by a spell, ability, or combat-damage assignment, without changing the source or type of damage. In general, cards that were printed with the term “redirect” now create replacement effects that modify where the damage will be dealt. “Redirect” is still used informally to describe what these replacement effects do.
Regeneration is a destruction-replacement effect. “Regenerate [permanent]” means “The next time [permanent] would be destroyed this turn, instead remove all damage from it, tap it, and (if it’s in combat) remove it from combat.” Because it’s a replacement effect, it must be active before the attempted destruction event. Abilities that trigger from damage being dealt still trigger even if the permanent regenerates. See rule 419.6b.
Reminder text appears after a keyword ability printed on a card and on cards that might otherwise be commonly misunderstood. Reminder text is text that is italicized and in parentheses in the text box of a card. This text provides a summary of the game rule or clarifies what the card does, but it isn’t itself considered rules text. See rule 207.2.
An attacking or blocking creature is removed from combat if it leaves play (such as by being destroyed or removed from the game), if it regenerates (see rule 419.6b), if its controller changes, if it stops being a creature, or if an effect removes it from combat. A creature that is removed from combat stops being an attacking or blocking creature and can no longer assign combat damage or have combat damage assigned to it. Any combat damage that’s already on the stack assigned to or by the creature will still resolve normally. See rule 306.2 and rule 310.4a.
A card removed from the game is out of play. The effect that removed the card may specify a way for it to return. Some objects use the expression “set aside” for situations in which a card removed from the game can return to play. See rule 217.7, “Removed from the Game.”