If Quicksilver, Brash Blur is in your opening hand, you may begin the game with him on the battlefield.
HasteHaste is a static ability.
If a creature has haste, it can attack even if it hasn’t been controlled by its controller continuously since their most recent turn began. (See rule 302.6.)
If a creature has haste, its controller can activate its activated abilities whose cost includes the tap symbol or the untap symbol even if that creature hasn’t been controlled by that player continuously since their most recent turn began. (See rule 302.6.)
Multiple instances of haste on the same creature are redundant. (CR 702.10)
Power-upPower-up is a keyword that adds additional rules to the activated ability that follows it. “Power-up — [Cost]: [Effect]” means “[Cost]: [Effect]. If this permanent entered this turn, this ability’s cost is reduced by this permanent’s mana cost. Activate this ability only once.”
Generic mana in the permanent’s mana cost reduces generic mana in the cost to activate its power-up ability. Colored and colorless mana in the permanent’s mana cost reduces mana of the same type, and any excess reduces that much generic mana. (See rule 118.7.) (CR 702.193) —
: Put a +1/+1
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) and a
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) counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on Quicksilver. (
ActivateTo activate an activated ability is to put it onto the stack and pay its costs, so that it will eventually resolve and have its effect. Only an object’s controller (or its owner, if it doesn’t have a controller) can activate its activated ability unless the object specifically says otherwise. A player may activate an ability if they have priority. See rule 602, “Activating Activated Abilities.” (CR 701.2) each
power-upPower-up is a keyword that adds additional rules to the activated ability that follows it. “Power-up — [Cost]: [Effect]” means “[Cost]: [Effect]. If this permanent entered this turn, this ability’s cost is reduced by this permanent’s mana cost. Activate this ability only once.”
Generic mana in the permanent’s mana cost reduces generic mana in the cost to activate its power-up ability. Colored and colorless mana in the permanent’s mana cost reduces mana of the same type, and any excess reduces that much generic mana. (See rule 118.7.) (CR 702.193) ability only once. Reduce the cost by his mana cost if he entered this turn.)