- Arrow Ship Cladding increases hit points by 20%, attack by 10% and range by 4.
- Copper Weapons, Bronze Weapons, and Iron Weapons increase attack by 10%.
- Copper Mail, Bronze Mail, and Iron Mail decrease hack and crush vulnerability by 10%.
- Copper Shields, Bronze Shields, and Iron Shields decrease pierce vulnerability by 10%.
- Burning Pitch gives +15% attack and 6x damage to buildings.
- Conscript Sailors decreases training time by 20%.
- Heroic Fleet increases attack vs myth units by 50%.
- Volcanic Forge (Leto): reduces pierce vulnerability by 10%.
They are critical in gaining control of water as they are the only warship available in the Classical Age. They are also effective in sinking enemy transports. Once in the Heroic Age, they will need support from other warships in order to be effective. They deal bonus damage against Hammer Ships and Transport Ships. Siege Ships will destroy them easily. Naval myth units are also a large threat.
As with other Atlantean ships, Biremes tend to be weaker, but faster and cheaper than their equivalents of other civilizations. This makes them more agile at sea and easier to mass.
"Atlantis fought war after war on the choppy Mediterranean Sea. Their warship - the bireme - was an excellent balance between ramming speed and maneuverability. The Pentekonter and Trireme were Greek attempts to improve upon Atlantean design that were very effective, though the bireme returned to prominence over time."