Sounds like you don't really know how to play GP well.
How to use Powder Keg(E):
- Place a barrel either next to you or in a bush.
- When enemy is close enough, place the 2nd/3rd barrels connecting from the first one and then throw your AA/Q on the first barrel to deal damage.
Even if the enemy is range, in order to kill the barrel next to you they have to get into your Q range to do so, making it a risky move for them to take damage just for 10 gold. Plus, hiding a barrel in a bush is a great setup, and thanks to that fast cast-time to throw down 2 barrels at the same time, enemies won't have time to react to the barrel's chain damage effect, or else they have to burn a trinket in a lane bush just to get rid of that hidden barrel.
How to not use Powder Keg:
-
When you're trying to start a 1v1 right away and you stupidly/blindly place a fresh barrel right in the enemy's face. You don't have time to proc it. Always try to set up early barrels to make a proper chain reaction by placing them either behind you or hide it in a bush.
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Throwing a single fresh barrel right in your lane opponent's face during early lane phase without thinking. You're typically throwing out a free 10 gold into their pocket.