The Multi-Tasker 4-in-1 Makeup Brush by Alleyoop is a must-have cosmetic tool, according to Jacinda's video review. This versatile brush offers four functions in one, making it a convenient addition to any makeup routine. The sponge side of the brush blends concealer flawlessly, while the other side can be used to set under-eye powder. The brush also features a perfect eyeshadow brush and an angled brush, which is ideal for brows or creating winged liner with eyeshadow. Overall, Jacinda highly recommends this brush, emphasizing its ability to perform multiple tasks effectively. With its versatility and quality performance, the Multi-Tasker 4-in-1 Makeup Brush is a valuable addition to any makeup collection.