Guiding Ariadne's counter trap effect issue
Guiding Ariadne requires you to reveal 3 cards when activating the effect for you opponent to choose from. 
If this is impossible because you do not have the required amount, you can not activate the effect.

This is why when Ariadne was a popular deck choice during PePe format, people often played 4 or 5 counter traps, to be sure they could resolve this effect even if a countertrap was already drawn.

Now it is possible you make a mistake and try to activate the effect and then notice you do not have 3 cards left.
What happens then is up to the discretion of the judge, but usually if no deck stacking due to an effect has occurred, you will be allowed to shuffle your deck and continue play.