@Nen-Suer
Be careful with the arrow trap that comes from both sides then, the best way that I found to avoid those traps is to just stick to the wall when I pressed the button, since the Arrows always travel along the central vector.
Also, to reach the bloodstain safely, fight each skeleton individually, kite them with an arrow and proceed slowly across the level. I lost quite a few bloodstains in 4-1 too, especially due to the Black Skeleton (Don't fight that one, unless you're absolutely certain of your dodging skills).
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
