well these are my ideas
- for ranks you can upgrade units, like skeleton soldiers
-more spells, like infliction which damages all units slightly
-increased resarch speed by 10%
-3rd level of upgrade
-spells, buildings and units have 50% time less to wait for it to appear
people can only atack people of the same tier
and you upgrade your rank from fame, like 2200 for rank 2 and 1 mill for 3.