Doomed Wall

 is a unit. It's a Prompt Blocker with good Health, but has a limited Lifespan.

Strategy
Doomed Wall costs gold more than a standard Wall, but has one more health and therefore provides 1 more absorb. When bought simply to be sacrificed in defense it is equivalent in cost for Health to buying a Wall and an Engineer, with the upside that the Engineer is made prompt and the downside that it does not provide the same granularity.

Doomed Wall, like other units with both Lifespan and Blocker, are at their most valuable when they are used to take fatal damage on the turn they would die due to lifespan. As Doomed Wall can't be clicked and therefore is always defending unless Frozen, players should generally attempt to use them this way. Against an opponent using freeze it may be safer to sacrifice the Doomed Wall on its second turn in order to avoid being countered. Units with constant Chill can effectively destroy them.