Caustic Arrow Trickster Level 82 Update | Path of Exile

With caustic arrow and toxic rain, You're mainly doing Damage Over Time Damage and it is chaos damage, Which means, you should take despair as your curse. For auras, Malevolence would also be a good option as your next go-to. Haste is helpful for toxic rain as multiple pods can hit and stack but you can only have one instance of caustic arrow damage over time on an ennemy, so the attack speed is semi wasted. The movement speed would still be good.

There is a passive skill called Whisper of Doom that lets you use an additional curse, is pretty close the the shadow tree, near some Chaos Damage nodes.