Batrider has a few responses which could be used at some places.

1. bat_ability_failure_04: "Ugh! Just swallowed a bug."

Use this as a rare (5% chance), non-repeating (speakonce) movement response.

2. Sticky Napalm has some good lines, why are they completely unused? They could be used as Sticky Napalm cast responses, with a low trigger chance, since Napalm is very spammable. A 5% or 10% chance would work fine I think, and also maybe a cooldown of 30 seconds.

Bat_ability_napalm_01: "You need a shower."
Bat_ability_napalm_02: "A little something to slow you down."
Bat_ability_napalm_03: "Look out below!"
Bat_ability_napalm_04: "Goo on you, baby!"
Bat_ability_napalm_05: "This stuff's sticky!"
Bat_ability_napalm_06: "I'm sappin' your will to live!"

3. bat_ability_firefly_03: "Scuse me while I cook this guy."

Use this as a cast order response, along with bat_cast_01/02/03/04. Flaming Lasso is his only single target spell, so it would fit well.

4. bat_ability_failure_02: "Sorry girl."

Use this as a rare rivalry response towards female heroes (Legion Commander, Broodmother, Drow Ranger, Luna, Medusa, Mirana, Naga Siren, Phantom Assassin, Spectre, Templar Assassin, Vengeful Spirit, Crystal Maiden, Death Prophet, Enchantress, Lina, Queen of Pain, Windranger, Winter Wyvern)