Motivate is a form of frenzy in which a unit is sacrificed to buff similar units by plus 50% more damage. Typically, frenzy cards buff only themselves, while this spell buffs many units in exchange for the sacrifice of a unit. Like many Shadow cards, it is not well-understood by players and is often undervalued. This translates into a good card that can be purchased inexpensively.
When used on a unit (preferably one nearing the end of its frenzy, or is near death, or is debuffed/CCed or some other compromised state), Motivate will kill the unit, allowing all units of the same kind as the sacrificed to get a damage boon.
Impending doom is not required, just to be clear. For example, anytime there are four of the same unit in play, their controller can gain an advantage from Motivating one. The remaining three will gain a 50% damage buff, for 3 x 150% = 450% damage, a net gain over the 400% damage of the initial four. Obviously, this is an extreme example. The duration is 20 seconds, upgradable to 30 seconds. The damage boost too is upgradable to +55%.
Sacrifices an own unit in order to spur on all other existing own and friendly units of the same kind in the current game. Affected units will deal 50% more damage for 20 seconds. Reusable every 30 seconds.