There are various effects to be found in Spiral Knights that affect you and enemies alike.
The victim bursts into flames. On enemies it deals periodic damage until they go out. On Knights it does the same, but you can spread the love around by touching enemies, who appear to be highly flammable.
Enemies are frozen in place and cannot move. Knights are frozen, and while they cannot move nor rotate they can still attack in that one direction. Other Knights can chip them out by attacking them.
Causes the enemy or Knight to be periodically interrupted for the duration. Also can arc lightning between any two with the status ailment, damaging those between.
Knights and enemies cannot be healed while poisoned, and have reduced attack damage. Enemies that are healed while poisoned take damage instead.
Knights and enemies affectd with stun have their movement and attack speed lowered.
Attacking causes enemies to take damage for the duration of the curse. Knights cannot access some weapons or items they have.
Enemies and Knights fall asleep, unable to do anything until they wake up. Sleepers slowly regain health until they wake up.