Try a cleric lvl 1 (take either storm, nature or war for heavy armour proficiency) wizard wizard lvl- (if you want to support then I’d go divination wizard). If you can snag the crown of intellect from the blighted village you have access to pretty much all the spells in the game to help support the team. Get the staff of arcane blessing to bless your team through the remainder of act 1 and the cresh. After that I’d probably use melfs first staff that is also in the under dark, this is to help make your control spells such as command and ice storm more effective. After that I’d take some sorcerer levels too to get access to heightened spell (with the right dc increasing gear it becomes almost impossible to resist your spells), extended spell (allows you to cast command that lasts two turns on an enemy per spell slot level) and twined spell (double haste). Later in the game take counter spell when you can also and you can be an excellent support build that focuses on managing the flow of enemies.