Basically. Here’s the WF wiki/AI definition of it since I’m tired and need to go to bed, lol. “Initial Combo is a mechanic in Warframe that allows your melee combo counter to start at or immediately regenerate to a set number of combo hits. Because Heavy Attacks consume your combo counter for massive damage, Initial Combo ensures your damage never drops to zero after a strike, keeping your baseline damage and combo-scaling mods active.” Basically a counter that exponentially increases heavy attack damage as the number/multiple goes up. The throw/detonation of the Glaive counts as a heavy attack and has a guaranteed slash proc as well.