This is a really awesome and well-polished game!
However, I think it would give more control to the player if rolling only spawns enemies instead of despawning them. This would keep an enemy from disappearing that you needed to continue your combo. Then, perhaps you could make it so that each spiked enemy has a combo requirement where if the player reaches a high enough combo they will disappear.
The highest score I could get was a 1920. Great entry!