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)
When this creature enters, target opponent may have you draw three cards. If the player doesn't, you
millFor a player to mill a number of cards, that player puts that many cards from the top of their library into their graveyard.
A player can’t mill a number of cards greater than the number of cards in their library. If given the choice to do so, they can’t choose to take that action. If instructed to do so, they mill as many as possible. Similarly, the player can’t pay a cost that includes milling a number of cards greater than the number of cards in their library.
An effect that refers to a milled card can find that card in the zone it moved to from the library, as long as that zone is a public zone.
Some spells and abilities mill a single card and then ask for information about the milled card. If more than one card is milled due to replacement effects and the effect of a spell or ability asks for information about the milled card, such as a characteristic or mana value, it gets information from each milled card and will get multiple answers. If these answers are used to determine the value of a variable, the sum of the answers is used. If that effect grants a player permission to cast or play “that” card, the permission applies to each of the milled cards. If that effect performs any actions on “the” card, it performs that action on each milled card. If that effect performs any actions on “a” card, the controller of the spell or ability chooses which card is affected. (CR 701.17) three cards, then this creature deals damage to that player equal to the total mana value of those cards.