The biggest difference with Legends of Runeterra is how the rounds work. In each round, the players take turns as attackers and defenders, but every time an action is taken, the opponent almost always has a chance to respond. This means that you cannot cast a series of spells and allies quickly, as in Hearthstone.
Here’s an example of how Turn Priority works:
Each player takes a card. The Defender goes first, and can cast any spells or allies in his hand if they have the mana to do so. If that player plays an ally, the turn priority goes to the attacker.
The attacker may then cast any of his spells or allies. Let’s say that in this case the attacker casts a spell to damage and destroy the defender’s recently called ally.
The move priority returns to the defender, who now has a chance to save his new ally from destruction. They just happen to have a spell to strengthen that ally’s health. They’re casting this spell.
The turn priority returns to the attacker, who no longer has options. Since the defender’s spell was played last, it is resolved first, giving his ally more health. The attacker’s spell deals damage to this ally. Now, if the attacker has allies called, they can go into battle.
And that’s how the whole round can play out:
The round starts, and the defender and the attacker take turns playing cards.
The attacker can start the battle by dragging allies to the central arena.
The defender assigns blockers, and both sides have the option to cast additional spells.
The battle is over.
Both sides have another opportunity to cast more cards until both sides have passed.
The round ends and the attacker and defender switch.