Marcel Ellermann enhanced the wowsims/cata and wowsims/mop repositories by delivering three features focused on improving simulation accuracy and code maintainability. He enabled fractional mana cost calculations by updating the BaseCost logic to use float64, addressing precision in resource management. Marcel also refactored data loading for zone names, removing external dependencies in favor of direct SQL database integration, which increased robustness. In wowsims/mop, he improved spell calculation accuracy by rounding floating-point values and introduced a reset mechanism for spellbooks. His work leveraged Go and SQL, demonstrating depth in backend development, data parsing, and code refactoring to strengthen simulation tooling.