Use the bag of marbles
You empty out the marbles into your hand. You have an idea!
With a skillful throw you roll the marbles across the floor towards the orcs. If your aim is just right then they will…
“ARGH!!” says an orc as it slips on a marble and flies into the air, landing with a crash on its bottom.
“Wot you doin’ on the floor you pillock?” says another orc, “Get up before you…WAHH!!”
“Wot’s goin’ on? I …YIKES!”
One by one the confused orcs slip on the marbles and go flying. Fortunately none of them land in the lava, but some of them do land on their heads and will have nasty looking bumps in the morning.
You run over to the sack to pick it up. One of the orcs sees you coming and tries to stand up, but slips on another marble and crashes to the floor with a thud. The falling orc’s foot lands heavily on the sack and the sound of something breaking comes from inside it. There’s no time to worry about that right now though, you need to escape before these orcs can get to their feet again!