First, we will use the DIII-D ITER baseline scenario (which has the ITER shape scaled down to fit within DIII-D’s vessel and many ITER-relevant plasma parameters) to show how challenging it is to do traditional gas-puffing control with newly emulated (“nerfed”) ITER actuation. This new DIII-D PCS capability will impose time delays and lags in the gas valves which will make it very difficult to regulate density even in L-mode, as expected in ITER. Then, in the main part of the experiment, we will employ the aforementioned advanced controllers in combination with the novel capabilities of the DIII-D pellet injection system. We aim to show how density regulation can be improved under ITER-relevant constraints and conditions, as well as during L-mode, H-mode, and transients, if the appropriate control techniques are used. Moreover, we will use several controllers (with an increasing degree of complexity both in the control algorithm and the model employed) to extract conclusions about the appropriate sophistication level needed in the controller design.