^ regarding that combo
5b CH Punish > D.Garu > 2a > 5b > d.Garu > 2a > 5b > 5c(2) > 2c > b.Bufu > SB.Agi > Dance
If the 5B was FC instead, you can get 1 more Garu rep, so that combo would look something like:
5b Fatal Counter> D.Garu > [2a > 5b > d.Garu] x2 > 2a > 5b > 5c(2) > 2c > b.Bufu > Ender (depends on which part of the screen you are/how much meter you have)
That as far as I've tested, seems to be the basic rule, if you're doing Garu loops and the starter was a Fatal Counter, you can add 1 more rep than usual and the combo will still work as normal, it adds like 500/600 more dmg that way.
EDIT:
Another example I was testing is:
(Corner) CH 2C > B.Zio > 5B > sweep > D.Garu > 2A > 5B > sweep > D.garu > 5A/2A > 5C (2) > 2C > B.Bufu > ender (with memento mori does like 8000 dmg)
if the initial 2C was a Fatal counter instead, you can get 1 more rep of that part in bold (and the whole combo does like 8600 instead too)