This may help a slight bit.
As for the combo system, you might work that out by using a variable to keep track of the current combo count, and play an animation based on the current combo count.
You could check if the combo count is > 0, then a sub-event, trigger once
And under the trigger once, use a "wait" action, for like 1 second, or however long you'd like it before the combo counter resets itself.
Then reset the combo to 0.
Hope that helps, or at least points you in the right direction.