@timemaster18 Not working for me. Tried on 4 maps (2 warmage and 2 RL difficulty). I made screenshots if needed. Not seeing 3 combos when wall charging minions on vtar.Edit: I tried a whole bunch of ways to get the effect now. Including spamming all lightning effects (charger, sapper, rod and ring). I couldn't get the extra combo point. While absence of evidence doesn't mean evidence of absence, if the effect exists its extremely rare/hard to produce.In your case I'm leaning that the extra point is in the hero kit.
Note that an old guide claims that dots and direct damage apply separate stacks but I have tested that with various traps (scorcher, spitfire, webspinner) and have never observed it. For example scorcher, tar, stinkeye slow only yields a max 3 stacks, not 4.