So if you play tess greymane and she somewhere down the line plays psychic scream, tess will finish her battlecry but everything played and summoned after the PS is for your oponent and not you. Is this intended?
Yes.
Same as when Yogg-Saron was still in standard and palyed fairly often - if one of the spells he casts causes him to change owner, then he’tll continue to cast the remaining spells for this new owner.
Tess works the same.
Don’t play Tess.
Problem solved.