The first set of lines that describe the actions taken by The Lady of Shalott to defy the curse are:
“With a steady stony glance—
Like some bold seer in a trance,
Beholding all his own mischance,
Mute, with a glassy countenance—
She look'd down to Camelot.”
Previously in the poem, it is mentioned that by looking directly at Camelot a curse would fall on her. So by by looking down with a stony, glassy countenance, she is defying it.
The second set of lines are:
"Still as the boathead wound along
The willowy hills and fields among,
They heard her chanting her deathsong,
The Lady of Shalott."
In this passage she has left the tower where she was confined to avoid the curse and invites death by singing her last song, challenging the curse once again.
