So this has probably been asked before but I can't seem to find a thread with a solid answer or any at all really. I would like to know how to change the glowing potion effect color when it's been applied via wearing a full set of armor. I have the potion set up just fine but it's currently just a white color and I would like to make it green. I know this is possible via ingame scoreboard commands but I would like to have it set to green without the player having to do anything but put the armor on.

Thanks in advance,
OIWeirdo

He means the effect that makes players visible behind walls. From spectral arrows. 

So, looking through the code, here are some thoughts. Note that there is probably a much better way of doing this that I'm just not aware of, but until someone mentions one, I'm offering this idea.

There doesn't seem to be any event fired during outline rendering that you can hook into to change the color at the last moment. But the color is determined by the entity's team on the scoreboard (specifically, the team prefix has a section-symbol color code, and that's what's used to get the glowing color). So if you could switch the entity's team just before the outline is rendering, then switch it back immediately after, you could change the glowing color without any other code seeing the incorrect team.

The relevant methods here are Entity#getTeam() and World#getScoreboard().addPlayerToTeam(String player, String newTeam).

 

The idea is that you'd hook into the RenderLivingEvent.Pre<EntityLivingBase> event and change the entity's team there to the color you want, then change it back in the RenderLivingEvent.Post<EntityLivingBase> event.