Hi Knowfear , i think your RC freinds are doing a lot of reading into the text here. All it says is that there are prayers of saints. This doesnt support their blasphemous claims (Christ is our mediator) one bit seeing as the bible says Colossians 1:2  To the saints and faithful brethren in Christ which are at Colosse: Grace be unto you, and peace, from God our Father and the Lord Jesus Christ.

Notice that. TO THE SAINTS WHICH ARE. They exist, we are saints. There is many other scriptures to support this. The real question to be askes about rev 5.8 is - who are the saints? ask your freind to show you from the bible that all saints are dead etc and im sure you will give your freind a proble. like all falshoods regarding biblical heresies, large things are built on such small foundations. That verse proves nothing.

Hope that helps a bit!