i'd say righteous glory is a trap item on tahm, since you dont want to be going out of your way to eat enemies. The only time you should be trying to eat an opponent is when you can auto them once without using q so you can quickly aa-q-aa them and then eat them, and even then only if you dont need to save a teammate.I usually find that if i go out of my way to eat an enemy i am too slow to make it in and get cc-ed,so i accomplish nothing while an ally is being killed.even if i teach the enemy i usually waste too much time on that and dont really contribute much. I would recommend a build that looks something like
and a tank item that you choose based on the circumstances. the stoneplate synergizes well with your e so you can lose almost all of your stoneplate health and then shield for that much. the others are protective items that help you save your team. i find
to be great on tahm since you can get to people to save them easier, as well as slow enemies you want to devour so you make it easier on yourself. if you are going to be play pure peel you probably dont want to aa people to keep the ms
as for some gameplay tips: you should only use your e shield if you think you are going to die if you dont, since you lose the grey health; you should also consider how low to get it before popping it. in lane you should use it earlier against hard cc opponents since if you wait too long they will stun you and you will die without popping it at all, while in team fights you can probably hold off a bit longer since people probably wont go out of their way to cc a support.
Watch your positioning. you need to stand as close to the most important/squishiest carry on the team as possible without being cced with them, so if the enemy has for example annie, you need to stand just outside of tibbers radius.
you can use your ult for cutting off your opponents avenue of escape, but you should think whether you are tanky enough to block them. also bringing a darius in the middle of a temfight can be pretty nice.another great use for the ultimate is getting a good back with your adc. for example when both carries have B.F. gold and are a bit low on health from occasional trades you can go for a fast back and then ult back to lane with your adc to secure lane initiative. you have to make sure to communicate with your adc about this. you can also use your ult as a pseudo-w if you are ganked. just plop it somewhere safe and let the person you are saving jump in. watch out, people tend to not think about this so you need to make people on your team aware of the possibility at game start. also dont do this if you can be stunned.
the important thing to note is that when you w someone you can save their flash by flashing yourself so you use only 1 flash instead of 2. also try to swallow people early vs heavy dot usere like malza since they can still die inside of you, and be mindful of ignite