Misty Step

Misty Step is the exit that costs a Bonus Action

At the table. Misty Step is a 2nd-level spell, cast as a Bonus Action, Verbal component only. You teleport up to 30 feet to an unoccupied space you can see. Because it only needs you to speak, you can cast it with your hands full or tied.

Why teleport beats walking away. Under the 2024 rules you don't provoke an Opportunity Attack when you teleport. Walking out of an owlbear's reach gives it a free Rend: +7 to hit, 2d8 + 5 damage, about 9.6 damage on average against AC 15 once misses are counted. Misty Step skips that attack and still leaves you your action.

The choice that matters is where you land, not whether you go. Thirty feet away from an owlbear is not safe: it moves 40 feet and climbs 40 feet. Land behind a door, across a gap, beside the cleric, or where the monster must walk past the fighter to reach you. "Can see" includes up: a balcony, a ledge, the top of a wall.

The common mistake is planning a Misty Step plus a levelled spell on the same turn. On a turn you can expend only one spell slot. Misty Step uses one, so your action that turn is a cantrip, a Dash, a Dodge, or an item.

Who else uses it. The SRD 5.2.1 Mage can cast Misty Step three times a day as a Bonus Action. When the party finally gets next to the enemy wizard, expect them to leave.

The human angle. Thompson's review of research on control found that believing you can do something about a threat often makes it easier to bear. Misty Step prepared is that belief made real: a caster in the second row plays more boldly knowing there is an exit.

Source: Thompson, S. C. (1981). Will it hurt less if I can control it? A complex answer to a simple question. Psychological Bulletin, 90(1), 89–101. doi:10.1037/0033-2909.90.1.89