As long as your life total is less than or equal to half your starting life total, Bane has indestructible.
Whenever another nontoken creature you control dies, target opponent may have you draw a card. If they don't, you may put a creature card with equal or lesser toughness from your hand onto the battlefield.
Bane's last ability looks at the toughness of the creature that died, not Bane's toughness.
10 Jun 2022
If Bane, Lord of Darkness is dealt lethal damage at the same time that its controller's life total is reduced to less than or equal to half their starting life total, Bane will have indestructible at the time state-based actions are performed and survive.