Velkoz-early-mid AOE monster. Has great CC, tons of pure damage and great ult for teamfights. On the other hand, his scalings are terrible, his range is not that great(aside from diagonal Q and R) and his spells are easy to dodge(Q is blocked by minions, W has a delay on 2nd tick, E has slow projectile)
Xerath-lane dominating artillery, with a bit weak midgame but godlike late. His CC is weak, but his range is one of the best, his endless spam can't be avoided by standing behind minions or using Windwall, so its easier to hit than most other skillshots. He is vulnerable to assassins, but if he is protected by his team-teamfight is a hell for enemy squishies. Lategame Xerath can blast enemy ADC for 50% of his hp with a single 3 sec cd spell, and he also has ult for finishing fleeing enemies as well as stun for ones who dare to come close.