As long as your devotion to white is less than five, Heliod isn't a creature. (Each in the mana costs of permanents you control counts toward your devotion to white.)
Other creatures you control have vigilance.
: Create a 2/1 white Cleric enchantment creature token.
Heliod is a resilient mono-white token engine that floods the board with 2/1 Cleric tokens, builds devotion to keep himself indestructible (and eventually a creature), and grinds out value while you go wide. You win by overwhelming with vigilant attackers, pumping the team with anthems, or assembling an enchantment/lifegain combo.
Indestructible commander that's hard to remove and dodges board wipes.
Repeatable token generation gives endless go-wide pressure and chump blockers.
Vigilance for the whole team lets you attack and defend simultaneously.
Mono-white pool means cheap, consistent mana and strong recursion/wrath access.
Token output is slow and mana-hungry at 4 mana per pair without ramp.
Vulnerable to exile-based removal and indestructible-ignoring effects (sacrifice, -X/-X).
Mono-white struggles with card advantage and ramp compared to other colors.
Heavily reliant on anthems/payoffs to convert small tokens into real damage.