At the beginning of each combat, until end of turn, each other creature you control gets +1/+1 if it has flying, +1/+1 if it has first strike, and so on for double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection, reach, trample, vigilance, and partner.
Partner
Build a wide board of creatures stacked with keyword abilities, then let Akroma turn every combat into a massive, scaling anthem that pumps your whole team based on the keywords they carry. You ramp into Akroma, deploy efficient keyword-soaked creatures (or grant keywords cheaply), and swing for lethal in mono-white aggro fashion.
Repeatable, free combat anthem that scales hard with go-wide boards
Self-statline is excellent: flying, first strike, vigilance, trample with vigilance letting her attack and block
Partner lets you pair a second commander for added consistency or a combo angle
Mono-white means clean mana, strong stax/anthem support, and resilient board wipes hate
Seven mana and the payoff needs a developed board to matter
Vulnerable to single-target removal—losing Akroma collapses the anthem
Mono-white struggles with card draw and ramp relative to other colors
A board wipe can undo your entire keyword-soup strategy in one card
Mono-white can't, but white's equivalents like Teferi's Protection and Flawless Maneuver protect the board from sweepers that would otherwise blow you out.