Historical Rules · 13 October 2023
Rule 702.154a
Official source text from the 13 October 2023 Rules release
Enlist represents a static ability and a triggered ability. Enlist means “As this creature attacks, you may tap up to one untapped creature you control that you didn’t choose to attack with and that either has haste or has been under your control continuously since this turn began. When you do, this creature gets +X/+0 until end of turn, where X is the tapped creature’s power.”