Let me start by saying I mostly play support characters. I've tried Banner of Command out a few times as Taric, since Radiance affects minions (or it did last time I made a point to check).

But to be honest it felt a bit underwhelming, don't get me wrong being able to buy Promote was cool but Surge felt cool too, it didn't mean it was that good.

I've looked up the base statistics of champions (http://leagueoflegends.wikia.com/wik...ion_statistics) to calculate Taric's dps and a "statistically average" champion.
I also calculated the dps of minion waves as a function of time with and without Promote(banner of commands active) and with and without the Banner of Command (passive)

Anyway from those numbers, Banner of Command is only better when solo/split pushing. If there is more than one player present then the bonus dps from Zeke's Herald(2450g) typically meets or exceeds the bonus dps provided by Banner of Command(2400g).

Is solo/split pushing a good idea for support? ('cause it sounds kinda like a death wish)
If not, who buys AP, Armor, and split pushes well?

Side note: The calculations I did assumed the full minion wave would be present which is a terrible assumption since the fighters tend to get picked off before the turret goes after the siege minion. I did not calculate for a lane being snowballed, because at 3 minutes a wave you're looking at a 9 minute 'cooldown' and a small window of opportunity.

TL;DR:
Zeke's Herald (2450g) + 1 ally > BoC (2400g) + promoted siege minion wave
So who is Banner of Command for? Because it's not most Supports.

I really wanted to vote between "Super Effictive" and "Niche".
The teamfight items are just waiting for players to notice that they can be abused. You are basically purchasing a 3rd summoner spell.
Well practiced teams can try to pick up two (or three) and keep the lanes constantly filled with super cannons. Its an easy way to push your objectives but is too subtle to show up on the "stats".

I used to run promote all the time (great way to get cs while off ganking or roaming), so i know it's value, but this is too costly.

If you drop the cost by 200 or did so something else to boost it, like let it heal the minions, add 10 Magic Resist, or have any minion in the aura net you gold with the kill, then we could get somewhere. Or at very least let me promote while i'm in the jungle. (running back to find a siege minion to promote doesn't do much, and if your in the right lane, it's likely to just get's countered).

The only use i can think of is rushing it to get the enemy tower down fast, so you can roam. But that has all sorts of drawbacks and counters.

I haven't used it before. The reason is because if I want to use the active ability I'm probably going to leave the lane. But the passive encourages you to stay in lane. Seems pretty conflicting. The only real use is for a tower rush strategy.

I don't know who would get this besides support or jungle, and either one seems like they wouldn't want it. If I see someone else using it well I might consider buying it. Until then I have no plans to even try it.

It's an item with potential, but still needs some tweaks. It gives cool states, but it's mostly a lane pushing item. Maybe if the aura gave a boost to champions that was good could make it useful.

Here's how you use it, each time you back, find a newly spawned cannon minion that is heading for a lane that you are NOT planning on going to, promote it, then rejoin the rest of your team who are probably clumped up in some other lane. force a teamfight by having your team push. If the enemy engages your team, they may or may not win. If your team wins, you get at least two towers. If you lose, they probably won't be able to stop the wave with the promoted minion in time to save their tower so you still get a tower. It's a late game item, do not get in in lane ever. That being said, it is an excellent late game item because it allows you to split push without risking your own hide.

I like it on Rammus late game (call me what you will) because it's bonus AP and armor with an aura/active combination I find more useful than Zhonya's active because I never really have to worry about dying.

Its a competitive play item.

This past season many team used a tactic called teleport promote. which is where you split off from your team during the team fight phase to push lanes and apply pressure. While being elusive enough to avoid ganks and quickly rejoin your team.

Banner of command cements this tactic into the meta.

No one has seen doubling these yet? One on the support and one somewhere else. The timing of lane pressure swings strangely in your favor.