Start your engines!Start your engines! is a static ability. If a player controls a permanent with start your engines! and that player has no speed, their speed becomes 1. This is a state-based action. See rule 704.
Players do not have speed until a rule or effect sets their speed to a specific value.
If a player has no speed and they are instructed to increase their speed by a certain value, their speed becomes that value.
There is an inherent triggered ability associated with a player having 1 or more speed. This ability has no source and is controlled by that player. That ability is “Whenever one or more opponents lose life during your turn, if your speed is less than 4, your speed increases by 1. This ability triggers only once each turn.”
Rules and effects may refer to whether a player has “max speed.” A player has max speed if their speed is 4.
Some effects refer to a player’s speed. If that player has no speed, their speed is 0 for the purpose of an effect that refers to speed. (CR 702.179)
When this artifact enters, conjure a card named Hangarback Walker onto the battlefield, then 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) on it.
Max speedA max speed ability is a static ability. “Max speed — [Ability]” means “As long as your speed is 4, this object has ‘[Ability].’” See rule 702.179, “Start Your Engines!”
If an ability granted by a max speed ability states which zones it functions from, the max speed ability that grants that ability functions from those zones. (See rule 113.6c.) (CR 702.178) — At the beginning of your end step, 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) on each artifact creature and/or Vehicle you control.