Barrel Blast needs changes.
Currently Barrel Blast without upgrades is too weak as a defensive tool and with Incoming Keg is too strong as an offensive tool.
Barrel has too little health to hide inside, and plants can simply use sprinting to run away from Barrel. It does not work as a means of retreating or defending Deadbeard, and using it defensively usually results in getting knocked out of barrel and dying.
With the Incoming Keg upgrade, Barrel becomes a very strong offensive tool. The extra speed makes sprinting away impossible and allows Deadbeard to use Barrel very aggressively, and this is becoming very abusable. Add this speed to Barrel being able to one-shot an Oak (effectively doing up to at least 300 damage) and Incoming Keg Barrel becomes a terrifying and frustrating weapon to play against.
Although Incoming Keg doesn't really make Barrel better defensively, it makes it great for surprising plants. It doesn't really matter that the Barrel has only 100 HP when you can time the fuse so that the plants have very little time to react to an explosive Barrel.
I think Incoming Keg makes Barrel too difficult to balance as it boosts Barrel's normal speed and "Lit fuse" speed. Incoming Keg should only boost Barrel's normal speed, as a boost to Barrel's speed with a lit fuse makes it too easy to abuse.
I think the stats on Barrel are broken and don't fit in a defensive class kit. I think it should be apparent that Barrel should not be able to one-shot Oak or Citron. Being able to one-shot Oaks and Citrons makes Barrel effectively a "tank buster", as well as making it too strong as a tool for pushes. It should only do 150 damage max, which is already pretty strong. Even without Incoming Keg, Barrel CAN work as a way to surprise plants. I also think Barrel needs a health buff to make it better as a defensive reaction tool.
I also noticed that Barrel seems to have a bug where you can sometimes damage Deadbeard inside Barrel without destroying the Barrel. This seems to happen often when you shoot a Barrel on its top, but it also happens just by shooting the Barrel.
Edit: It turns out you can only do 300 damage WITH the Incoming Keg upgrade.