T-2's are a level below Primes. They make good 2nds in a Tower and good backups to a Prime.
A T-2 can run a Tower but usually two high talents are required to do close to the job a T-1 can. The best T-2's are twins, siblings or two that compliment each others abilities where one can path or port better than the other.
Sometimes you will find a T-2 rating for clairvoyants, finders and empaths.