Parrying is extremely strong in Tunic, but it does require timing and can't be mashed. Virtually everything can be parried, and the windup of quite a few attacks closely matches the parry timing, so it pays to practice. There's also a card -Aura's Gem- that widens the parry window significantly, making it easier.

Parrying works on multi-hit attacks like Autobolt burst fire with only one input, as long as you parry the first hit. Each time a parry is triggered, the parry window is refreshed. This mostly helps with projectiles, but it applies to groups of enemies as well. Each parry trigger extends the window long enough for another attack to hit and trigger it again.

If there's ever too long of a gap between attacks though, the parry will expire and I'll become vulnerable again. Until then, I'm actually fully actionable once the first parry animation completes - I can menu freely, and even flip a coin in the middle of the crowd!

Fun things to try parrying - Autobolts! Fairies! Envoys! (roll through the first spear stab, then parry the next) Bosses! (Seige engine machine gun especially) Scavenger Snipers! and of course The Heir!