Requirements :
1 - Host must select the challenge
2 - Host must pick up the artifacts
3 - Players 1 & 2 have to stay together in each crypt
4 - Optional : Don't pick up small artifacts - only run for this achievement (took us 2-3 days)
5 - Stop at exactly 5 (no more !) - For us, we had a mix of 3 medium and 2 larges
6 - Host trigger the rescue fire. both must escape.