Legends of Runeterra has many card effects that are common enough that they get their own keyword - a word or two that immediately tells you how the card works. Let's take a look at the Strongest keyword.
Highest Power, with ties broken by highest Health then highest Cost.
The strongest wills come in the smallest packages...or they could come in the Strongest units. Because they're...you know, the strongest.
Strongest is defined as being the unit with the highest Power on the table, followed by highest Health if there's a tie, followed by highest Cost if there's still a tie. If you're facing against a 5/2 and a 3/3, the 5/2 is the Strongest.
Keywords that Work Great with Strongest
Strongest is a condition for other effects, telling you how they function. As such, it could theoretically be used with any of the keywords, such as Stun or Frostbite.
Playing Against Strongest in Legends of Runeterra
Your Strongest unit will always be the Strongest unit, until something better comes along anyway. You'll just have to live with that fact, or make sure a tie exists to make it harder on your opponent. If every ally is a threat, then being the Strongest doesn't matter as much.
Example Legends of Runeterra Strongest Cards
Ashe Frostbites the Strongest enemy unit when she attacks, preventing them from being much more than a simple body-block. Her Level 2 ability keeps them from blocking at all, completely removing them from the fight.
Rimetusk Shaman Frostbites the Strongest enemy unit, performing a similar function as Ashe. However, as it is done at the start of the round, she functions on every turn, not just when you attack.
The Rekindler revives the Strongest allied Champion that died this game, providing an instant influx of Power on the table. Pair him with something huge like Darius or Tryndamere for maximum carnage!
The Harrowing does not specify that they have to be your units, meaning it will revive the six best units that have died this game, friend or foe. Immediately bring them to bear, and overwhelm your opponent with an onslaught of heavy hitters!