ISIS has seemingly been successful in mobilizing advocates from heterogenous backgrounds. Such diversity is symptomatic of the organization’s heavy investment in strategic messaging and identity construction to gain legitimacy. This study examined the multimodal discursive properties of ISIS’s narrative in its communique, Dabiq. It undertook a Multimodal Critical Discourse Analysis of the representation of in-group and out-group actors implementing Van Leeuwen’s socio-semantic inventory. The results showed that the in-group members are deliberately specified, hence foregrounded, and at the same time, the diversity among them is highlighted as an inseparable hallmark of ISIS’s movement. Therefore, no racial, geographical, or cultural line was drawn apropos its participants to ensure more inclusion. Conversely, the perceived enemies are framed as diverse yet homogeneous entities textually through generic references and addressing them collectively regardless of their potential dissimilarities and visually by categorizing them through religiously, culturally, or nationally distinguishable features. It acts as a legitimation tactic by which striking against one enemy justifies striking against others. The combination of these strategic multimodal framing tasks serves as a propaganda tool for ISIS to intensify polarisation, enhance in-group participation, and ultimately facilitate mobilization.