Mortek Crawler Cauldron Vs Chainrasps.

[Spears]

The Crawlers cauldron states "equal to or greater than the unmodified bravery characteristic of the target unit" Chainrasp horde have a bravery characteristic of 6, however the unit has a bravery characteristic of 10 while it includes a dreadwarden.

Does the dreadwarden bravery 10 count as a modifier?

[Overread]

Sometimes it helps to quote the whole rule as the context and specific words can make a bit difference 

"In addition, a Chainrasp Horde has a Bravery characteristic of 10 instead of 6 while it includes a Dreadwarden."

In this case the Dreadwarden isn't applying a modification to the bravery it is straight up replacing the base number. So long as the unit has a Dreadwarden its unmodified bravery is always a 10.