Buffing your cards can create some amazing combos (hello granting attack power to Braum), so it’s important to know exactly how both granting and giving works in Legends of Runeterra.
If a card grants a stat boost, that buff will last the entirety of the game (so long as your unit doesn’t die of course...and sometimes even if it does).
On the other hand, if a card gives a buff to a unit, that buff will only last the round, so plan accordingly.