But still it won't appear in any combat log?! I tested it in many ways over the last three days but I never saw some extra damage or heal from a follow up attack. I'm really confused about this one.
I have had few time experimenting with the Lava Whip skill. However, I noticed that the "Off balance" debuff lasts way less than when performing a successful interrupt or block. Also, it would greatly help if the tooltip of Flame Lash was redesigned.
The follow up is simply using flame lash ability second time. If first one was performed on stunned/rooted/knocked down target it will put them of ballance (meaning powered attack will knock them down) and second flame lash cast on them during the duration will not cost mana and do damage and self heal according to tooltip. Follow up lash has also different animation.
So, for example: 2h morphed charge with root, followed by 2 flame lashes (only one costs mana) and then charged attack for knockdown.
Or stone fist, 2 lashes, charged attack. etc.