AD Carry protection and safety.
Durability and crowd control
Guard allies you cast spells on and those that are very nearby. If you or a guarded ally would take damage, you're both hasted and granted a shield.
Impairing the movement of an enemy champion marks them. Your allies heal when attacking champion's you've marked.
After 10 minutes gain 8 Armor and 8 Magic Resist and increase your total Armor and Magic Resist by 5%.
Heals and shields are 5% stronger and increased by an additional 10% on targets below 40% health.
Creative tools and rule bending
Bonus MS towards nearby allies that are movement impaired or enemies that you impair movement on.
Get a free biscuit every 3 minutes, until 12 minutes. Biscuits heal and permanently increase your max mana.
Guardian on Tahm allows him to eat a teammate that is about to take damage, shield, and gain the bonus Movement Speed to allow him to run away and re-position to spit them out.
Over the course of the game Guardian block a significant amount of damage if you're able to reliably stay near a teammate to block damage in key moments.
Like Braum, the combination of [Q] slow and Tahm's natural health stacking allows you to provide decent healing in lane fights.
The Armor and Magic Resist of Conditioning pairs very well with champions who buy an early Locket to make for a strong mid-game teamfight.
If you're looking to play aggressively in lane, Iron Skin can be a good alternative for tanking damage.
Revitalize synergizes well with Tahm's passive shield, FotM, Locket, and healing from Redemption.
Approach Velocity is a great rune on Tahm to assist getting into range to [W] a CCed teammate, and for follow-up chase and damage on an enemy you have hit with [Q].
Biscuit Delivery allows you to sustian through tough poke lane that might abuse your short range during the laning phase.