Surprisingly this ally, costly as it is, can found itself quite at home in a 2-heroes deck (or even a 1-hero one for those crazy people who attempt it :D) since at least it avoids its most negative effect. It can also be marginally successful in a Visionary Leadership Fellowship, but I don't think it's worth the trouble. Any way I think the greatest cost of this ally is having to give up playing its very good heroes versions.
Ally. Cost: 4. 3 1 2 3
Denethor gets -1 for each damaged hero you control.
Discard Denethor if his is 0 or less.
"Denethor is of another sort, proud and subtile, a man of far greater lineage and power, though he is not called a king." Gandalf, The Return of the King
Encounter at Amon Dîn #57. Leadership.