<insert name here, the minion king> (Looks like a caster minion of your team's color)
Passive- Blending in- If <insert name here> hasn't cast a spell in the last 15 seconds, enemies will mistake him for a normal caster minion. His health bar will be replaced with a minion health bar, and clicking on him will show typical minion stats and items, as opposed to his actual stats and items.
Q- Rally- Rallies his fellow minions, setting their focus on a specific target, and causing their attacks to hurt that target more than usual. In addition, <insert name here> gains an anti-turret aura, decreasing the armor and MR of all enemy turrets he is near.
W- Ready the Cannons!- <insert name here> takes on the appearance of a siege minion, gaining a shield which provides additional attack speed and attack damage for a short time. If the shield is broken, <insert name here> loses the benefits and returns to caster-minion form.
E- Reinforcements- Summons a wave of minions from <insert name here>'s current location. The wave will consist of 3 caster and 3 melee minions, with an addition cannon or super minion depending on level. These minions are worth 1/3rd of the usual minion gold when killed, but otherwise have the same stats as their regular counterparts. They will follow <insert name here> and attack whatever he attacks instead of charging down a lane, but die after 30 seconds.
R- Level up- <insert name here> Calls all allied minions to himself, combining into a super-minion form. He gains a base amount of Health and AD from the transformation, plus an additional amount of health and AD per minion absorbed by the skill. (Minions summoned with Reinforcements give stats at half the ratio). At the end of the duration, all minions absorbed are spit back out at 3/4ths their starting health.
...actually, that would be a pretty fun champion. Riot, we need more minion champions!
...you may think it's weak, but imagine the scenario. A fresh wave of the 6 usual minions and one cannon minion has just arrived mid, and you are level 3. You cast reinforcements, making the total number of your minions 13, plus you. Then you cast Rally, buffing ALL your minions, and causing them to focus on the enemy mid. Assuming Rally causes an overall 10% damage increase at level 1, and you've got one point in all 3 skills, then your damage total would be...
Minion attack * number of minions * attacks per second for all three types together =
13(6)(1.25) + 27(6)(.67) + 40 = 247 *1.1 =271 damage a second, from just minions, not even counting your attacks. Of course this doesn't take into account minions being killed (which they will), resists, or the time it takes them to get in range. Still, you've got an army doing insane damage at early levels on top of your basic damage, and even turret diving the enemy at no risk. Used incorrectly, you're giving the enemy a little free gold. Used properly, and you're killing the enemy very quickly with minions.