Arena turns League of Legends into short fights between six teams of three. Lose a round and your team loses health; keep adapting until one team remains. With no lanes, towers or farm to protect, each fight is shaped by item offers, Stat Anvils, Augments, Power Flowers and the closing Ring.
Instead of preparing for a standard role, build a repeatable combat trick: isolate one opponent, survive the opening burst, control the plants or make the Ring impossible to cross. During scouting, decide who starts that plan and which enemy cooldown can stop it.
Garen: build the whole round around Judgment
Arena Garen should be narrower than his Summoner's Rift version. Wait for key crowd control, use Decisive Strike (Q) to clear a slow, activate Courage (W) before the return burst, then keep Judgment (E) on one target. Berserker's Greaves and Phantom Dancer support this spin-first plan. Spin To Win and Lightning Strikes reward the same attack-speed investment; Goliath buys time to finish the rotation. Save Demacian Justice (R) until shields or a major heal have been spent.
Let control create the damage
Arena lets tanks turn crowd control into a damage engine. Alistar can pair Cruelty with Courage of the Colossus: Headbutt and Pulverize now produce damage and shields, not only setup. Threaten Headbutt without spending it immediately, keep the target inside your ally's range and body-block while the combo recharges. Bard can instead take Chauffeur, ride a mobile teammate and look for Cosmic Binding into terrain. Both plans make a compact arena hostile rather than imitate a lane support.
Make movement itself the trap
Singed does not need a proxy lane. With Rylai's Crystal Scepter, Liandry's Torment and Don't Chase, spread poison across the route opponents must use as the Ring closes, then fling the focus target back into your team. Anivia solves the same problem from range: place Glacial Storm behind the enemy, wall the safe exit and save Flash Frost for the forced path. These builds win by deciding where the other team may stand.
Choose an engine, not four isolated Augments
Each Augment should start your pattern, multiply it or keep you alive long enough to repeat it. Spin To Win, Lightning Strikes and Goliath all serve Garen's spin; Cruelty and Courage of the Colossus serve Alistar's control chain. Reroll a famous option when it does not support your engine. Synergy matters more than four high-ranked names pulling in different directions.
The secret Stat Anvil build: Shardholder and Shardblade
Shardholder is not an Augment but a special Stat Shard offer. Choosing it grants Shardblade, which blocks future item purchases and increases every Stat Anvil's effect by a random 20% to 100%. You stop building an inventory and turn the champion's raw stats into the build.
To stay eligible, buy Stat Anvils and no shop items. You may keep the free Prismatic item supplied by the mode. Community-maintained documentation places the first Shardholder chance after 10 purchased Stat Anvils and guarantees an offer after 25; those hidden thresholds are not shown in the client.
Item-granting Augments can break the route. Do not take Prismatic Egg before finding Shardblade: its Prismatic item removes Shardholder eligibility. Buying and undoing an item does not rescue the attempt. Gamba Anvil, Stats On Stats and later Hone Shardblade support the plan, while normal items, item anvils and item quests can end it.
Do not force the secret. Ten early anvils can leave you weak when their stats miss, and the lobby may eliminate your team before the payoff. Commit when the first shards are useful, teammates can cover early rounds and an Augment lowers anvil costs or adds shards. Otherwise, pivot to items.
Use the champion catalogue as a starting point
Baron Buff's free Arena catalogue gives every champion three to five handcrafted tips with named items, Augments and a concrete round plan. Use it to find an engine, then adapt to your team, opponents and actual offers.