At "Mass" we enter Heaven with Jesus in the presence of all the Angels and Saints as He offered Himself to the Father on Good Friday over 2,000 years ago.
We can pray to God at any time and anywhere but at Mass we can pray to God, with God and in God dying on the cross at Calvary because Good Friday is present on the altar at the "consecration" of Mass. We can offer the sufferings and Sacrifice of Jesus who is the "Lamb Of God" to God the Father in atonement for the Sins of the World and also receive Jesus risen from the dead present in the Sacrament of Holy Communion. Mass is the most powerful prayer we can make. Biblical Scholar Jimmy Seghers explains the Mass and all it's significance.