Intense nerve pain and delirium. That's just one of the weakest side effects of a small dose of Euryale's toxin that she can inject in a victim via any serpent that she can form from her body. The venom will paralyze the victim, give them intense nerve damage that is strong enough to stop a heart with ease, but somehow doesn't.
Depending on the victim, it also induces them in a coma which will put them in a dreaming state where they either live out a nightmare fueled by their fears, they will relive unwanted memories that will remind them of any mistake's they've made. A simple bite from any of Euryale's serpents is enough to not only corrupt them but torture them; physically and mentally. A simple bite is more than enough for the Daughter of Chaos to subdue any Mortal and place them under her spell.