League of Legends has never been defined as pay-to-win. The purchase of cosmetics does not influence your results but allows you - for lack of skill - to have style. However, it happens that a few lines of code bring strange situations into the flaw like the huge glitch on DJ Sona that made her immune to certain types of crowd control. This is precisely what's happening with Veigar, although this bug is not as impressive as that.
This glitch was brought to light by Reddit user BabyGeeezus. using veigar's E, after the cage disappears it looks like the stun will still be around for a few moments after the spell has worn off. One might have thought it was an isolated mistake, but the bug repeated itself twice in the game, leaving little room for doubt.
However, we strongly advise against rushing into the store and getting this skin. Riot Games hates players who abuse loopholes in their code, and the punishments can be dire at times. From a simple temporary ban to a permanent ban.
We hope that the studio will react quickly and fix the problem as quickly as possible.