Teclis is normally guarded by Caradryan. And camped in a big unit.I've found the combination of 3 Trebuchets to whittle down the unit followed by a charge from KotR with Lord tends to do the trick. Because of Lance formation, there aren't too many attacks hitting first and the Bret Lord will be in a challenge with Teclis (Gauntlet of the Duel - Challenge MUST be accepted). 4 S6 attacks at WS10 re-rolling misses and wounds plus one from the trusty nag tends to see minor characters die a rather grisely death lol.
Besides, the whole point of why Teclis is hard to kill is because he sends out more successful spells than an Oxbridge spelling comp.
Anyone who's anyone won't let your Gauntlet of the Duel near him without either spell blasting you, or have Teclis exit out of the back of the unit.
At which point, Caradryan accepts/issues a challenge and slays your Lord.