Target blocking or blocked creature you control gets +1/+1 and gains
first strikeFirst 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 or double strike (see rule 702.4) 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.
Giving first strike to a creature without it after combat damage has already been dealt in the first combat damage step won’t preclude that creature from assigning combat damage in the second combat damage step. Removing first strike from a creature after it has already dealt combat damage in the first combat damage step won’t allow it to also assign combat damage in the second combat damage step (unless the creature has double strike).
Multiple instances of first strike on the same creature are redundant. (CR 702.7) until end of turn. If it has a hat, it gains
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) until end of turn. If you and that creature each have a hat, the creature gains
tripleTripling a creature’s power and/or toughness creates a continuous effect. This effect modifies that creature’s power and/or toughness but doesn’t set those characteristics to a specific value. See rule 613.4c.
To triple a creature’s power, that creature gets +X/+0, where X is twice that creature’s power as the spell or ability that triples its power resolves. Similarly, an effect that triples a creature’s toughness gives it +0/+X, where X is twice that creature’s toughness. Tripling a creature’s power and toughness gives it +X/+Y, where X is twice its power and Y is twice its toughness.
If a creature’s power is less than 0 when it’s tripled, tripling that creature’s power instead means that the creature gets -X/-0, where X is twice the difference between 0 and its power. Similarly, if its toughness is less than 0 when tripled, it gets -0/-X. If one characteristic’s value is negative but the other isn’t when both are tripled, it gets -X/+Y or +X/-Y, as appropriate. (CR 701.11) strike until end of turn.