The mysterious bard is an Anemo character and before unleashing wind on the enemy you will first need to upgrade the character a little. Here is the complete list of the materials needed for Venti.
Venti Ascension Materials
Vayuda Turquoise Sliver
Number required: 1
Vayuda Turquoise Fragment
Number required: 9
Vayuda Turquoise Chunk
Number required: 9
Vayuda Turquoise Gemstone
Number required: 6
Hurricane Seed
Number required: 46
Cecilia
Number required: 168
Slime condensate
Number required: 18
Slime Secretions
Number required: 30
Slime Concentrate
Number required: 36
Venti Talents Upgrade Materials List
Slime condensate
Number required: 18
Slime Secretions
Number required: 66
Slime Concentrate
Number required: 93
Teachings of Ballad
Number required: 9
Guide of Ballad
Number required: 63
Philosophies of Ballad
Number required: 114
Tail of Boreas
Number required: 18
Crown of Insight
Number required: 3
If you're looking to upgrade your Ganyu here is the complete list of the materials you'll have to farm to Ascend the character and her talents.