scmJS docs

Deaths

True when the number of units of the type the player has lost is at least, at most or exactly the amount.

Every player has a death count for every unit type, whether or not that unit is ever on the map, and Set Deaths can change it. That makes the death counts of unit types a map does not use the usual place to keep numbers: a counter, a timer, a state. Each is a whole number from 0 to 4,294,967,295.

Condition 15 · Deaths(Player, Unit, Comparison, Amount);

Argument Takes Stored in the condition
Player a player or group bytes 4–7
Unit a unit type, or one of the unit classes bytes 12–13
Comparison At least, At most or Exactly byte 14
Amount a whole number, 0 to 4,294,967,295 bytes 8–11
Deaths("Current Player", "Cave (Unused)", Exactly, 3);