The unlucky adventurer is a Pyro character character and before unleashing his might on the enemy you will first need to upgrade the character a little. Here is the complete list of the materials needed for Bennett.
Bennett Ascension Materials

Agnidus Agate Sliver
Number required: 1

Agnidus Agate Fragment
Number required: 9

Agnidus Agate Chunk
Number required: 9

Agnidus Agate Gemstone
Number required: 6

Everflame Seed
Number required: 46

Windwheel Aster
Number required: 168

Treasure Hoarder Insignia
Number required: 18

Silver Raven Insignia
Number required: 30

Golden Raven Insignia
Number required: 36
Bennett Talents Upgrade Materials List

Treasure Hoarder Insignia
Number required: 18

Silver Raven Insignia
Number required: 66

Golden Raven Insignia
Number required: 93

Teaching of the Resistance
Number required: 9

Guide to Resistance
Number required: 63

Philosophies of Resistance
Number required: 114

Dvalin's Plume
Number required: 18

Crown of Insight
Number required: 3

If you're looking to upgrade your characters in Genshin Impact some of them will require Onikabuto and here where to find them