Random number generator. In this context, leaving something up to pure chance whether or not a combo can work from one enemy to the next.
Funny thing is, this guy's complaints are largely unfounded.
One Small thing can drastically change DMC3-4's combat for the better
DMC4 already had this employed for the Alto/Bianco Angelos (With shields, they'll break combos, without, they're free game), Frosts, Assaults, Blitzes, Mephistos/Fausts (Those specifically had a combo break after so long without a cloak AND if they fell too far they could re-cloak), Chimeras (You can't even launch those without knocking them away) and Chimera Seeded Scarecrows/Assaults unless you disabled them first with gun spam.
I think the Cutlasses also had a similar combo-break mechanic in play too.
In short, besides Gladius (Which did fly away if you were wailing on them if they were embedded in the ground after so long), Basilisks, the Mega/Normal Scarecrows and... again possibly Cutlasses because I don't have enough time with them recently to say for certain, DMC4 already employed this kind of thing.
That makes DMD sound extremely frustrating. Right now it's just difficult, but add that level of frustration to a game mode that's already extremely hard, and you'll have 2 broken controllers per household.
I came here to chew bubblegum and kick ass, and I'm all out of bubblegum. http://d24w6bsrhbeh9d.cloudfront.net/photo/5062421_700b.jpg