Warcry:
4530 Armor, giving 93.9% damage reduction.
15286 Effective Health
+107% Attack/Speed
Each kill adds 4 seconds to Warcry time, maxing out at 60 seconds.

Hysteria:
535 Damage
1.23 Energy/second

Warcry armor calc (equation taken from wiki):
700 (base armor) x (1 + 1.575 ([Steel Fiber]) + 0.45 (Glad Aegis) x (2.14 (strength))) = 4531

Only danger is being 1 shot from across the map, so keep moving. Could replace Power Drift with Enemy Sense to provide enemy mapping when companion dies. Or use support cat to provide synergistic healing and crit buff.

Use high crit, combo multiplier based melee - try [Nikana] (Zaw or Prime) paired with a stat-stick [Daikyu] with Amalgam Daikyu Target Acquired for more undying synergy. Gladiator Aegis adds to crit chance based on combo multiplier. All adds up to undying red crit rain :)

Note some mods in build are not maxed, to fully max requires 2 additional forma or another umbral forma.