I kinda wish that sigils just lowered the level of my creatures to the level of the sigil. I think it’s really cool to fight them at an even match, and I love using them, but it’s hard to me to be able to stay at the level range I need.
My suggestion would be for sigils to simply use your highest creature level instead.
I feel like Sigils should generate as they are now, but without the level. Make them only usable at the summoning altar, and have it cost a small amount of resources to summon an enemy group that has a level based on the average of your creatures, or weighted to make it a fair/challenging fight. If you have any of the breeding perks it makes it incredibly hard to breed a team low enough to fight in Sigils as they are now.
FYI: Zack said recently in the Shoutbox that he has plans for a significant change to the sigil system, but that it will be a while before he gets to it because he is prioritizing urgent fixes and easy/quick changes.