User blog comment:Emptylord/Sandbox/Custom Patch Notes/@comment-12904660-20150426072231

Ever thought of giving promote different strategic uses? Perhaps something like this:

Melee minion deal bonus damage to minions and heal based on that damage. Promoted melee minions are designed to push a minion wave to enemy towers, but they don't deal more damage on other targets, such as turrets.

Caster minion's attacks ricochet after hitting their target, searching another enemy minion and dealing increased damage on each strike, but starting with a low base damage (primairy target takes full normal damage). Additionally, this minion deals large amounts of bonus damage to super minions. This promoted minion is designed to defend against large incoming enemy minion waves, but fail to really push as hard as a promoted melee minion would.

Cannon or siege minions could probably just solely deal hefty increased damage to structures. Their purpose is to demolish the enemies base. They have however no means of performing better against minions then normal siege minions and are likely to die against other siege minions.