The present disclosure provides combinations or sets of two antigen binding molecule, in particular asymmetric combinations of such antigen binding molecules. Each of the two antigen binding molecules is composed of a targeting moiety with specificity for a tumor associated antigen fused to either the VL or VH domain of an antibody Fv domain specific for CD3. Once the two antigen binding molecules bind to their target antigen on the surface of a cell, the complementary VL and VH domain are capable to associate with each other thereby reconstituting the functional CD3 specific Fv domain and non-covalently dimerizing the two antigen binding molecules. The thus on-cell formed trispecific heterodimeric antibody molecule is capable of engaging and stimulating cytotoxic T-cells for tumor cell destruction.