Registration and battlefield location determine the applicable rules.
Clans need level 4 or higher for official castle-siege participation. Other players can enter as unregistered participants. Check the siege registration and schedule for the actual castle.
Kills within the active battlefield do not increase the PK counter or Karma, and deaths there do not drop items. Registered attackers and defenders lose one quarter of normal death XP both inside and outside during the siege. Unregistered players receive that reduction only inside the battlefield.
Interlude prevents the defending side from destroying its own castle gates. Do not propose breaking those gates as a defender tactic.
The level-68 Warsmith summon needs 46 A-grade Crystals, then consumes 21 B-grade Gemstones per minute. Its area attack can hit allies too; it cannot damage castle gates, walls or siege headquarters.
Official siege participation requires the appropriate clan level and registration for the castle. Being near the battlefield or joining a party is not the same as registering the clan. Check the actual castle’s siege information before moving supplies and players. A participant’s registered or unregistered status affects which death rules apply, so settle it before the siege begins.