Rift Quest:The Care and Imprisonment of Changelings  

Gnarladon is a boss of a zone wide life invasion event named Arboreal Assault and Cinderon is a boss of a zone wide fire invasion event named March of the Gedlo. Be prepared to wait a long time, continually checking the Silverwood map to see if it's being invaded. You simply need to be near the bosses when they die for quest credit.

For the Messenger of the Vigil Tear go all the way back to Port Scion Bay where you first entered Silverwood and talk to the Messenger of the Vigil(6090,3950) and she will give you the tear you need freely.