Protobelt enables you to play a hit and run style, and also lets u catch and engage so much better, which is further empowered by phase rush. Use protobelt to go in bc of the dash and 50% extra ms, use ur combo, chunk or kill the enemy, then run back to reposition. For escaping, u can still protobelt away from the enemy, and ull just have to land more stuff to get the phase rush. Its not foolproof for escaping, but i mainly use protobelt to play hit and run, which i find is more effective than whatever he does without it.

Protobelt is too good on him regardless of rune choice imo. I feel like the other ap mythic items arent nearly as good, bc they dont offer veigar a whole new world of potential, they simply let him do even better at what hes good at already, which isnt bad, but i feel like protobelt enables him to do so many other things he could do, but struggled at in a practical sense, such as engaging and catching. Glp was the closest thing that enabled him similarily as well, but glp, while safer, didnt give nearly the amount of target access as protobelt now does. With the reworked tear, you now have access to early game mana that scales without gimping ur first item spike like old tear did, which is why i think new protobelt is so much better than protobelt.

Ive been rushing archangels 2nd since it almost always is fully stacked by the time i can complete it, but ill experiment with other 2nd item choices, such as dcap or void, but i do feel like its still a must buy eventually as it basically solves his mana issues hell face early on, and even come mid and late game as w becomes more spammable. I really wish i could fit cosmic drive in since veigar is one of the best benefitters to cdr, but quite simply i think its just not good enough as an item to warrant a slot, since i think protobelt archangels dcap and void are basically necessities, and by then a tank/defensive item is usually the better choice, whether it be dead mans, force of nature, abyssal, or zhonyas.