Slovan don't play a summer league.
Wouldn't underestimate them at all - they dealt with Dundalk fairly comfortably a couple of years back, and even beat the mighty UCD 1-0 in 2015. Not as bad as Legia, but maybe on a par with Malmö? They've beaten LoI teams every time bar one, which was a draw back in the 90s. One player at the Euros at the moment.