Chandra, Pyromaster

While casting the copies created by the third ability, timing restrictions based on the card's type (such as creature or sorcery) are ignored. Other restrictions, such as "Cast [this spell] only during combat," are not.

The card exiled by the second ability is exiled face up. Playing it follows the normal rules for playing that card. You must pay its costs, and you must follow all applicable timing rules. For example, if it's a creature card, you can cast it only during your main phase while the stack is empty.

To activate the first ability, you must target a player but you can choose to not target any creatures.

While resolving the third ability, you create the copies of the card in exile and cast them from exile. You can cast zero, one, two, or all three copies. The card itself isn't cast. It remains exiled.

Because you're casting the copies "without paying their mana costs," you can't pay any alternative costs for the copies. You can pay additional costs, such as kicker costs. If the copies have any mandatory additional costs, you must pay those.

If the first ability resolves but the damage is prevented or redirected, the target creature still won't be able to block that turn.