Stunning a unit has two effects in Artifact which essentially combine the disarm mechanic with the silence mechanic. The first effect is that it prevents the unit from attacking in the combat phase, much like the disarm effect, though additionally it prevents abilities from being triggered. The secondary effect is less obvious, but at least equally as powerful: your opponent can’t play cards on their stunned unit, it becomes untargetable, and it ‘loses’ its color for a turn. This means no buffs of any kind can save it from an incoming fatal blow.
Two heroes are able to stun their enemies. Earthshaker’s Fissure dismantles his enemy neighbors for a round, saving his small health pool a bit longer. But it’s Tidehunter who steals the show. His ability Ravage has the same cooldown as Earthshaker’s Fissure (4 turns) and stuns enemy neighbors for the remainder of the round. However, there is an additional 50% chance for any other enemy to also get stunned. Talk about a one-up.
Stun effects are scarce, and considering their power, understandably so. You can use it to completely disrupt the opponents offense and significantly weaken their front line. Although it may seem tempting to trigger stun effects whenever they’re on cooldown, that can backfire. A lot can happen in the four turns it’s on cooldown. Use it when you have other critical tools to turn the tides in your hand. Otherwise, of course, it’s a great defensive means to stabilize when your opponent is pushing a bit too hard.