At its absolute most basic, foundational level, every single competitive arena battler relies on a very simple childhood game.

In this digital version, the triangle consists of Swarms, Area-of-Effect (Splash) Damage, and High Single-Target Damage.
The Core Mechanics
The rules of the arena are simple: Swarms overwhelm Single-Target units; Splash Damage obliterates Swarms; and Single-Target units destroy Splash Damage.

Every time you place a card on the battlefield, you must ask yourself: "Which part of the triangle am I playing, and what does the opponent have to counter it?"
Never build a deck with only one side of the triangle.Reaction time matters.A well-timed Zap can save your Single-Target unit from a Swarm. Exploiting the Rules
If your opponent only has one 'Scissors' (Splash spell) in their deck, and you bring three 'Papers' (Swarms), they literally cannot stop you.

You send your first swarm to force them to use their spell; the second they do, you unleash your primary swarm attack safely.
Troop TypeThe TargetWhat it Loses ToMultiple Small UnitsHigh DPS single-target tanks, Princes, P.E. Here's more about tower rush check out our own website. K.K.AsWizards, Valkyries, Bomb Towers, The LogAoE UnitsSkeleton Armies, Minion Hordes, Goblin GangsHigh health single-target units, Mini P.E.K.K.As, Heavy Spells Why the Meta Changes
If Splash units become too strong, nobody will play Swarms, and Single-Target units will dominate the ladder.

Always respect the fundamental rules of combat before attempting complex maneuvers.