Error:

[COST][Counter-Blast 1], and perform one of the following. …

If you have four or more units with different card names, perform two instead of one, …

… and if you have five or more, perform all instead of one. …

Correct:

[COST][Counter-Blast 1], choose any number of your units, and perform one of the following. …

If you chose four units, and all of the chosen units have different card names, perform two instead of one, …

… and if you chose five or more units, and all of the chosen units have different card names, perform all instead of one. …

Reason for Correction: