Talk:Guild Base/@comment-27.32.248.110-20181103235524/@comment-2600:1702:45F0:A010:45:4C16:7CC4:529E-20181104034446

"The collective maximum level for all Custom NPCs combined is part of the NPC Data Storage. Higher-risk dungeons award the guild with a higher amount of levels if conquered. This limit can be further increased by upgrading to a higher-ranked dungeon, using cash, and so on."

So Yes, they can increase the Level Limit with cash items. If that wasn't the case, then weak guilds can have their bases be easily Destroyed by stronger guilds since they can't build a good defense.