Like many other heroes, Axe has a several responses which could be enabled and used for some events.

1. Culling Blade has an aoe boost upon killing a unit. The flavor text says that Axe unleashes a war cry, which grants the speed bonuses.

So how about making him yell upon killing something with Culling Blade?

They would basically play as cast responses, but have a certain condition to only play when it is a lethal cull. They should be audible to everyone, or at least to allies, and not only to Axe alone.

These lines would fit well here.

axe_berserk_06 *yelling*
axe_berserk_07 *yelling*
axe_berserk_08 *yelling*
axe_berserk_09 *yelling*

Currently, these are used as Berserker's Rage cast responses. But I think we can take them away from there, he'd still have enough cast responses for it.

2. On other other end, how about using his failure lines for failing a Culling Blade?

Similar to the previous suggestion, but these would play when it is a failed cull. They should probably have a short delay before playing, like a half or full second.

These are his failure lines.

axe_failure_01 "Axe misjudged?"
axe_failure_02 "Axe misjudged?"
axe_failure_03 "You are tougher than Axe thought!"

Also, I feel like these were used for this before.. or maybe I'm just remembering wrong.

3. Some other unused sounds could be sprinkled into already existing response rules of Axe

- axe_spawn_06 "Axe lives." -- could be used as a Respawn response.
- axe_spawn_07 "Axe swings his blade." -- could be used as a rare leveling up response for Counter Helix. (LevelUpAbilityIsCounterHelix*)
- axe_attack_08 "Here you break." -- could be used as a cast order response (CastOrder)
- axe_regen_02 "Axe's edge grows keen again!" -- could be used for what it was ment for, as a rare regen response.

4. Some killing responses suggestions

- axe_cullingblade_02 "Wheat before a scythe." -- This line could be used as a Counter Helix multi-kill response (KillsIsCounterHelix*IsDouble/Triple/Quad/QuintupleKill) with a high respeakdelay or speakonce

- axe_rival_30 "Axe hates the keen folk!" -- could be used as a rivalry response towards Sniper, Tinker, Techies, Shredder and Gyro

- axe_rival_31 "Axe cut you in four!" -- could be used as a rivalry response towards Phantom Lancer

And these could be used as very rare rivalry responses towards Phantom Lancer
- axe_rival_32 "Axe cut you into more than four!"
- axe_rival_33 "Axe cut you into more than four! Nine?"
- axe_rival_34 "Axe cut you into more than four! Twenty?"
- axe_rival_35 "Axe cut you into more than four! Hundreds?"

These two lines, why are they used as regular kill responses? Would be better if they were used for what they were ment for: Killing an enemy with Culling Blade after a blink. The response rule for this already exists, containing one of the 3 responses which were ment for it (axe_blinkcull_02). These 2 lines could be moved to that response rule, away from regular killing response rules. Axe has enough regular killing responses since new ones were recorded.
- axe_blinkcull_01 "Not so fast!"
- axe_blinkcull_03 "No escaping Axe!"

* IscounterHelix criterion is not set up yet.