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) (This creature can attack and
as soon as it comes under your control.)
You may
exertTo exert a permanent, you choose to have it not untap during your next untap step.
A permanent can be exerted even if it’s not tapped or has already been exerted in a turn. If you exert a permanent more than once before your next untap step, each effect causing it not to untap expires during the same untap step.
An object that isn’t on the battlefield can’t be exerted.
“You may exert [this creature] as it attacks” is an optional cost to attack (see rule 508.1g). Some objects with this static ability have a triggered ability that triggers “when you do” printed in the same paragraph. These abilities are linked. (See rule 607.2h.) (CR 701.43) this creature as it attacks. When you do, target creature can't block this turn. (An exerted creature won't
untapTo untap a permanent, rotate it back to the upright position from a sideways position. Only tapped permanents can be untapped. (CR 701.26) during your next
untapTo untap a permanent, rotate it back to the upright position from a sideways position. Only tapped permanents can be untapped. (CR 701.26) step.)