Rage is a total knockback multiplier. The reason rage "scales" best with base kb is because of simple math. Let's say it takes 200 kb to KO someone. Let's assume for simplicity that kb = base kb + kbg/100 * damage. Move A has 100 base kb and 100 kbg, so it KO's at 100% (100 + 100/100 * 100 = 200). Move B has 150 base kb and 50 kbg, so it also KO's at 100% (150 + 50/100 * 100).



However when you add a multiplicative factor to it, they reach the 200 kb threshold at different %'s. At max rage the multiplier seems to be pretty close to 1.15, so let's just use that for the math. 200 = 1.15(100 + 100/100 * A). 200 = 1.15(150 + 50/100 * B). The damage needed for A to KO is 74%. The damage needed for B to KO is 48%. A 26% difference despite both KO'ing at 100% without rage.



If you play around with all the numbers you will notice a clear pattern for how they affect the difference in KO%'s. Basically as kbg gets smaller and as bkb gets bigger, the % difference for KO's due to rage will increase. Also the scariest character in the game with rage is Luma. They probably switched the numbers for bkb and kbg by accident or something which lead to that monstrosity lol. That's my guess anyway.



As for how rage scales with %, I think some of the people that have tested it came to the conclusion that it doesn't start until like 30 something % and ends at 150%. I'd wager it scales linearly starting from that point until 150.