You get the Nitrates from a guy in Surfall and give them to the zookeeper in
the Akaon zoo.
This works great for the kolandi quest but helps if you have a friend Druid
who can teleport you to Steamfont and both bind in Surefall.
The tonic is lore so you can only have one.
Halfling illusion is in the guildhall in Erudin.
Languid Pace helps your Roots last longer because htey save less often.
Tashan helps there too since htey have a lower save.