tldr: make war cry mana cost similar to other “spammable” skills like lightning, fire ball, blessed hammer.
The reason no one is making war cry barbs is because of the extreme mana costs of the skill. The huge cost was probably set because it’s a level 30 skill. The mana cost should reflect how the skill is used instead of what level it is. Let’s compare it to frozen orb. It’s also a level 30 skill and has a similar mana cost to war cry (44 mana at level 40 vs 49 of lvl 40 war cry) but it has all those projectiles that make the mana cost justified.
War cry is used much more like “spammable” skills e.g. lightning, blessed hammer, fire ball etc. and should therefore have a mana cost similar to those skills. In my opinion it should have the same low mana cost as blessed hammer. A war cry barb would never be able to compete with the damage output or clear speed of a hammerdin or a sorceress anyways but it would still make it less of a pain to play and increase build diversity.
Below are some examples of mana costs:
lvl 40 war cry: 49 mana
lvl 40 frozen orb: 44 mana
lvl 40 lightning: 27.5 mana
lvl 40 fire ball: 24.5 mana
lvl 40 blessed hammer: 14.7 mana (lol)
(edited the post to make it a bit easier to read)