If you get sucked in on your turn and haven't used your action you can try to get out.

@Soulstar888
No need to be rude. This is a forum where people discuss and help each other out.
Furthermore, how someone plays the game is entirely their own decision. You wanna sell that magic item? Sure, just find someone who wants to buy it. This could be a whole quest.
DnD is about fun, not about the "right" thing to do. It's a roleplaying game after all.
If the player later thinks "damn that bag of devouring would have been useful now" is a whole other story! ;-)

Most people are forgetting the obvious. It is a strength CHECK, not a strength SAVE. It is also repeatable. Take the ready action on your turn so when the BBEG makes a melee attack you place the bag in the way. BBEG fails the roll and is eaten, or succeeds the roll and you do it again next turn. To people saying this bag is useless, it can eat a tarrasque 25% of the time and the tarrasque can't legendary resist it.

"However, once each day, the bag swallows any objects inside it and spits them out into another plane of existence. The GM determines the time and plane." - why not talk to your GM about binding the place it spits out to somewhere. Could be an interplanetary same day shipping item. 

What happens if somebody who is wearing a bag of holding is pulled in the bag of devouring?

there is a 50 percent chance that the creature is pulled inside the bag

Am I supposed to flip for it? Or is it more of a 50% They succeed their Strength check, 50% they fail their Strength check?

Also this would work wonders with Hex if you wanted a little extra assurance.

I had a hag give to my players. The Barbarian got swallowed up and escaped.

You could use bead of force on someone and stuff em in the bag

Got one of these is my old campaign. The DM was shady with the descriptions but we always turned a bag out to see if anything good fell out. Nothing came so we were a little sketched out. Didn't do any else with it till the wizard identified it. Very grateful to have been cautious for once. 

My prosthetic arm don’t count lol and it’s a trick holding that’s why

Stick it on a Tarrasque's toe, possibly let it get killed by it

also hilarious if the party fails to Identify it and just assumes its a bag of holding.

Quote from shao_lung >>

My first DM once told me about a game he was in where a bag of devouring was turned inside out. What resulted was the emergence of a multi headed beast kind of like a hydra but with bags over all of its heads.

 Bag of Beholdering

you can shove somebody into it

My rouge places it on the ground in doorways baddies are likely to come thru. 

I had a bag of devouring once.. but after I "tested" it out by putting a man we were interrogating head into it and he instantly lost it due to an ac of 9 and 5hp, my dm sort to destroy it :) I guess he realised since our party constited of a 20 strength cleric focusing on grapple attributes, I was going to end every battle with decapitation. 

Forbidden vacuum cleaner

Hmm.

Quote from SwiftStormwolf >>

This seems to contradict itself.  It says you can escape with a DC 15 strength check as an action, but are devoured at the start of your turn.  How can you take the action to escape if you are devoured?

 You use your reaction to try to escape if you're placed or pulled in. At the start of your turn in initiative, should you fail, you are devoured. 

Quote from DrTacos >>

Most people are forgetting the obvious. It is a strength CHECK, not a strength SAVE. It is also repeatable. Take the ready action on your turn so when the BBEG makes a melee attack you place the bag in the way. BBEG fails the roll and is eaten, or succeeds the roll and you do it again next turn. To people saying this bag is useless, it can eat a tarrasque 25% of the time and the tarrasque can't legendary resist it.

 easily blocked by a gm though, the bag still acts like a bag until you put part of yourself inside it so trying to counter some one wielding a sword would likely result in the incredibly delicate bag that breaks completely if torn or pierced in any way copping some unreasonable wear during the struggle to force a part of the enemy in to it. im not saying it cant be used like that, im just saying i wouldn't rely on it working more than once when you really need it