One powerful rune choice for Darius is Ingenious Hunter, which reduces item cooldowns for each unique takedown you participate in. This can be incredibly useful when paired with items like Sundered Sky and Eclipse, which have important active effects that can turn the tide of a battle.

Sundered Sky: Sundered Sky is an excellent choice for Darius due to its unique passive, Lightshield Strike, which empowers his next basic attack against a champion to critically strike for 175% damage and heal him for 140% of his base AD (+ 6% of his missing health). This passive synergizes well with Darius's kit, allowing him to deal significant burst damage while also healing himself, making him more durable in extended fights. Sundered Sky's passive converts excess healing beyond Darius's maximum health into bonus health for 6 seconds. This bonus health can provide Darius with a temporary buffer against incoming damage, allowing him to stay in fights longer and potentially turn the tide in his favor.

Eclipse: Eclipse is another strong option for Darius, providing him with both offensive and defensive capabilities. Its Shieldbreaker passive enhances Darius's ability to cut through enemy shields, while its Crescent active grants him a temporary shield and movement speed boost upon damaging an enemy champion. This can be particularly useful for Darius to engage or disengage from fights effectively.

Stridebreaker: Stridebreaker is a versatile item for Darius, offering both offensive and defensive utility. Its active ability, Swift Slash, allows Darius to dash a short distance in a target direction, dealing damage to enemies hit and slowing them by 60% for 2 seconds. This can be used to engage on priority targets, escape dangerous situations, or reposition in team fights.

Sterak's Gage: Sterak's Gage is a defensive item that can help Darius survive burst damage and extended fights. Its unique passive, Lifeline, grants Darius a shield equal to 75% of his bonus health when he takes a large amount of damage within a short time frame. This shield can provide a significant amount of protection, allowing Darius to withstand burst combos from enemies or survive focus fire in team fights.