Xerath

His long range and poke can force you out of lane

Zed

High burst damage and can escape veigar cage with R or W.

Azir

If you can cage Azir, you should be able to 1 shot combo him.

Katarina

Everfrost can deal with katarina as you can hit her if she escapes your cage but if she gets kills early she will be very hard to deal with.

Vex

Vex's slightly longer range and fear make it hard to trade even if she gets ahead but if you are ahead then you can beat her.

Fizz

Probably the hardest matchup for veigar as fizz does high damage and can escape your cage.

Syndra

Orianna

Malzahar

You need to get fed against him or he will just stop your teams damage with his ultimate.

Yasuo

A skill matchup but I think yasuo is slightly advantaged due to a better early game and his wind wall.

Yone

With everfrost against yone, you can keep killing him to the point of him being useless. Make sure to buy boots early as his they often use R to get out of your cage so you can dodge it.

Aurelion Sol

Even matchup as you both are scaling champs, but when he stands still to use his abilities on the wave you can punish with W and Q to do a large amount of damage and get passive stacks easily.