Page 272 of the DMG states:
When a creature tries to move through a hostile creature's space, the mover can try to force its way through by overrunning the hostile creature
A creature can try to tumble through a hostile creature's space, ducking and weaving past the opponent.
Both are optional Bonus/Actions a creature can make to move through another hostile creature. Now, my question is:
1.) Does a creature need to be 5 ft away from the hostile creature to do these actions?
What if there is a hallway 5 ft wide and a hostile creature battling a friendly creature that is positioned between you and the hostile. If you had enough movement to tumble/overrun, could you do it 10 or even 15 feet away, explaining it as a running start?
2.) If so, what is the consequence of failing the check?
More importantly, what square do you end up in on a failed Tumble/Overrun?