Bennett's one of the most prayed-for character in the game despite being a four-star character. This is all because of his ability to heal any character at such a high rate all the while increasing your ATK while in the field--a tier S support indeed!
Bennett's elemental burst, Fantastic Voyage, triggers the healing and ATK buff. Bennett's healing scale is based on his Max HP, but you don't have to prioritize increasing his HP since any flower of life artifact can do this for you, not to mention that increasing Bennett's character level improves his max HP as well.
What you want to focus on is his base ATK because this is where his buffing scale is based. The description of Fantastic Voyage reads:
"Bennett performs a jumping slam attack that deals Pyro DMG, creating an Inspiration Field for 12 seconds.
Inspiration Field:
- If the health of a character within the AoE is equal to or falls below 70%, their health will regenerate each second. The amount of HP restores scales off Bennett's Max HP.
- If the health of a character within the AoE is higher than 70%, they gain an ATK Bonus that scales based on Bennett's Base ATK.
- Imbues characters within the AoE with Pyro."
Now you may think that increasing his ATK is the key to having an incredible ATK Bonus so you do this by prioritizing ATK main stats and/or sub stats on your artifacts. By doing this, you are enhancing only the damage that his normal/charged attack and elemental burst can deal but will not in fact increase the ATK of whoever is within Fantastic Voyage's Inspiration Field. This is because Fantastic Voyage's ATK Bonus is based only on his base atk, not Max ATK. Consequently, any improvement on his artifacts will NEVER increase the ATK Bonus that his elemental burst gives off.
There is only one way to improve his elemental burst's ATK Bonus, and that is increasing his character and weapon level . By this, his Base ATK will also increase, hence, a more satisfying ATK Bonus from his elemental burst
