The "MULTI" workshop series has set a number of multi-level modeling challenges, each designed to allow competing multi-level modeling approaches to demonstrate their capabilities and/or to tease out their limitations. The challenges therefore have been serving a three-fold purpose: First, they have allowed technologies to demonstrate their abilities. Second, they have pointed out where technologies still fall short of providing optimal modeling support. Third, they have provided a basis for comparing competing technologies, often revealing the trade-offs implied by certain design choices. The MULTI Warehouse Challenge described in this paper is the fourth installment in this series, defining a new unique set of demanding modeling challenges.