In the third level of the first pack, there is a long plain that descends two steps. You will then encounter a monster. Soon afterwards, there is a portal to climb into.
Go straight ahead and jump at the end (be careful not to fall off.) Stay in the portal and wait. It's as simple as that!
Falling off at the end as a result of moving right too far at the end, and getting killed by the monster are all risks in this level.
"Monsters follow you and attack you."
"Press 'r' to respawn."