FlashFlash is a static ability that functions in any zone from which you could play the card it’s on. “Flash” means “You may play this card any time you could cast an instant.”
Multiple instances of flash on the same object are redundant. (CR 702.8)
ConvokeConvoke is a static ability that functions while the spell with convoke is on the stack. “Convoke” means “For each colored mana in this spell’s total cost, you may tap an untapped creature of that color you control rather than pay that mana. For each generic mana in this spell’s total cost, you may tap an untapped creature you control rather than pay that mana.”
The convoke ability isn’t an additional or alternative cost and applies only after the total cost of the spell with convoke is determined.
A creature tapped to pay for mana in a spell’s total cost this way is said to have “convoked” that spell.
Multiple instances of convoke on the same spell are redundant. (CR 702.51) (Your creatures can help
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) this spell. Each creature you
tapTo tap a permanent, turn it sideways from an upright position. Only untapped permanents can be tapped. (CR 701.26) while casting this spell pays for
or one mana of that creature's color.)
Double strikeDouble strike is a static ability that modifies the rules for the combat damage step. (See rule 510, “Combat Damage Step.”)
If at least one attacking or blocking creature has first strike (see rule 702.7) or double strike as the combat damage step begins, the only creatures that assign combat damage in that step are those with first strike or double strike. After that step, instead of proceeding to the end of combat step, the phase gets a second combat damage step. The only creatures that assign combat damage in that step are the remaining attackers and blockers that had neither first strike nor double strike as the first combat damage step began, as well as the remaining attackers and blockers that currently have double strike. After that step, the phase proceeds to the end of combat step.
Removing double strike from a creature during the first combat damage step will stop it from assigning combat damage in the second combat damage step.
Giving double strike to a creature with first strike after it has already dealt combat damage in the first combat damage step will allow the creature to assign combat damage in the second combat damage step.
Multiple instances of double strike on the same creature are redundant. (CR 702.4)
Other tapped creatures you control have
hexproofHexproof is a static ability.
“Hexproof” on a permanent means “This permanent can’t be the target of spells or abilities your opponents control.”
“Hexproof” on a player means “You can’t be the target of spells or abilities your opponents control.”
“Hexproof from [quality]” is a variant of the hexproof ability. “Hexproof from [quality]” on a permanent means “This permanent can’t be the target of [quality] spells your opponents control or abilities your opponents control from [quality] sources.” A “hexproof from [quality]” ability is a hexproof ability.
Any effect that causes an object to lose hexproof will cause an object to lose all “hexproof from [quality]” abilities. Any effect that allows a player to choose a creature with hexproof as a target as though it didn’t have hexproof will allow a player to choose a creature with a “hexproof from [quality]” ability. Any effect that looks for a card with hexproof will find a card with a “hexproof from [quality]” ability.
“Hexproof from [quality A] and from [quality B]” is shorthand for “hexproof from [quality A]” and “hexproof from [quality B]”; it behaves as two separate hexproof abilities.
“Hexproof from each [characteristic]” is shorthand for “hexproof from [quality A],” “hexproof from [quality B],” and so on for each possible quality the listed characteristic could have; it behaves as multiple separate hexproof abilities.
Multiple instances of the same hexproof ability on the same permanent or player are redundant. (CR 702.11).