Sei

Sei is a Tier 4 naval combat unit introduced in Version 6.0. It operates as a large, high-damage ship that specializes in long-range bombardment and area denial in water-dominated maps. Sei complements other naval support units by forming powerful offensive groups that can raze enemy structures and units; it is often used both as an attacking spearhead along waterways and as a mobile defensive gunline to control deep water.

Sei’s armament consists of two distinct weapon systems: a launcher that fires homing explosive projectiles in volleys and a dual large-bullet mount that delivers heavy, accurate shots. The launcher fires at a rate equivalent to 6 projectiles per volley and 1.33 volleys per second, has an inaccuracy of about 7 degrees, deals 42 damage per projectile with 45 area damage on impact (~4.3 tiles), and features homing behavior. The large-bullet mounts fire in pairs with each mount producing 3 shots per volley (two mounts produce a combined volley pattern at 2x 1.5/sec with each mount effectively doing 0.5 volleys/sec), have about 1 degree inaccuracy, and deal 57 damage per shot. These combined weapons give Sei exceptional single-target and area damage output, able to obliterate both swarms and higher-health targets.

Practical use and interactions:

• In offense, Sei thrives when there are clear naval routes to enemy Cores or structures. Its high sustained fire forms a “death ball” when supported by other naval units; pairing with Oxynoe for damage boosts and Cyerce for healing makes front-line formations exceedingly difficult to stop. Aegires can act as a healer/defender alternative, though it is more costly for equivalent support roles.
• In defense, Sei can substitute for static turrets in deep water, holding choke points and denying enemy ships or amphibious assaults with its mix of explosive area damage and heavy bullets.
• Against Sei, prioritize destroying it before its projectiles connect with critical blocks because its damage potential is large enough to threaten Cores. It is commonly considered the strongest Tier 4 unit and can out-duel units specialized at killing high-health targets. Because Sei is a naval unit, it is immune to the Wet status; strategies that rely on making targets wet to amplify certain ammo types are ineffective. Specifically, combining Surge Alloy rounds with water-based effects like a Tsunami is less effective than using Blast Compound rounds and Cryofluid against it. Fast, high-damage naval units such as Foreshadow can often strike first and deal meaningful damage before Sei can retaliate, especially on open-water maps where flanking is possible.
• Sei’s projectiles include homing missiles; do not underestimate its ability to hit mobile targets.

Development history and notable facts:

• Introduced in Version 6.0. Subsequent builds adjusted its health, range, speed representation, item capacity, and removed its command limit. Notable numeric changes include health increases from 10000 → 10500 → 11000, a temporary range reduction from 35 → 32 → 35, speed normalization to tiles/second, and item capacity changed from 160 → 150.
• The in-game description refers to armor-piercing bullets, but none of the Sei’s weapons currently have armor penetration mechanics; this mismatch likely stems from later additions of armor-penetration mechanics elsewhere and was not retroactively applied to the unit description.
• The unit’s name references the sei whale, Balaenoptera borealis. Its mounted swarmer sprite resembles an older swarmer sprite with a different color palette.