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.

The best thing that can be said for this card is that it is a fantastic fit for the theme. Denethor becomes increasingly depressed by hero injuries until he commits suicide.

But that's not very good value for four. He starts at 3 willpower, which is good for his cost, but won't stay there without healthy heroes or willpower boosts that could've enhanced other heroes. He has neglible attack and at 2/3 is too fragile to be a repeat defender without help (that you probably wouldn't want to give a suicidal ally). Even in a Gray Wanderer deck, if the lone hero is damaged he becomes a 2 wp quester for 4 cost with no positive abilities whatsoever. In fact, he's the only 4-cost unique ally in the game who doesn't have some sort of positive ability.

One of the very worst choices for Messenger of the King