Foreword
There is an important distinction to be made between siege and terror comps. Siege relies on actual siege units like Rhino or Goliath as a frontline, while terror focuses completely on dealing damage to the ship without a concrete frontline.
Both teams focus on dealing direct damage to the enemy ship while more or less ignoring their units. These teams are strong because while players can gear their units with high resistances and defensive stats, they cannot gear their ship with defensive stats. As a result, even against well-geared whales, siege/terror has good performance. Furthermore, siege/terror have very quick games, which allows for quicker climbing in RTA, where traditional comps can very often stretch into 3 minute slugfests.
If you have any questions or feedback, please don't be afraid to dm Adepht who is the author of the guide adepht#0561.
Siege Playbook
Due to the guide being massive, very detailed and also to allow the author to easily edit it, it will be kept in the original form as a google doc.
Link to the guide:
Siege Playbook