Gwynevere, Daughter of Gwyn

When Gwynevere, Daughter of Gwyn becomes
the target of a spell or ability, sacrifice her.
As long as Gwynevere, Daughter of Gwyn is on
the battlefield, non-creature permanents you
control have indestructible.
When Gwynevere, Daughter of Gwyn is put into
the graveyard from the battlefield, return it to the battlefield transformed.
—
"Amazing chest ahead"