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)
Whenever one or more other creatures die, Soul Shredder perpetually gets +1/+1. This ability also triggers if Soul Shredder is in your graveyard.
CrewCrew is an activated ability of Vehicle cards. “Crew N” means “Tap any number of other untapped creatures you control with total power N or greater: This permanent becomes an artifact creature until end of turn.”
A creature “crews a Vehicle” when it’s tapped to pay the cost to activate a Vehicle’s crew ability.
A Vehicle is “crewed by” a creature if that creature was tapped to pay the cost to activate that Vehicle’s crew ability.
If an effect states that a creature “can’t crew Vehicles,” that creature can’t be tapped to pay the crew cost of a Vehicle.
Some Vehicles have abilities that trigger when they become crewed. “Whenever [this Vehicle] becomes crewed” means “Whenever a crew ability of [this Vehicle] resolves.” If that ability has an intervening “if” clause that refers to information about the creatures that crewed it, it means only creatures that were tapped to pay the cost of the crew ability that caused it to trigger. (CR 702.122) 1
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SacrificeTo sacrifice a permanent, its controller moves it from the battlefield directly to its owner’s graveyard. A player can’t sacrifice something that isn’t a permanent, or something that’s a permanent they don’t control. Sacrificing a permanent doesn’t destroy it, so regeneration or other effects that replace destruction can’t affect this action. (CR 701.21) two creatures: Return Soul Shredder from your graveyard to the battlefield.
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) only as a sorcery.