I'm not going to say Tez is easy, because my Nobu is kind of overkill even with just her own buffs. But one thing that helps is you have your seals back. You can't revive at that point though, so they are only useful for NPs or healing.
My own suggestion is to find a strong ST Avenger (best I was able to get was L100 NP2 Jeanne d'Arc Alter, but maybe you can find better on your own list?), two suitable supports (I went with Merlin and Castoria, half expecting a slower battle, but Waver would have been a better option given his own buffs), a second suitable damage dealer with a high damage CE (ST Berserker or Avenger is best due to Tez being a Ruler) to summon forward and a plugsuit MC.
For the first three bars, Jeanne was more than enough between NPs and crits to do a bar each turn. The final bar has two stages. When you reach it, Tez gains resistance to card damage, so you want NPs. Swap out a support to get your second damage dealer. If you need to, use a couple of Command Seals here so both damage dealers can use their NP. Hopefully his bar is drained by both attacks. When that happens, he refills his HP one last time, locks out your regular cards and gives you full NP charge so you have to use those attacks to finish him that turn, or restart the battle. If you have any buffs left, use them now. Figure out the best order for your NPs (my Nobu went last for extra trait damage against divine enemies) and fire. Hopefully that does the job.
