Sure, playing a 5-mana enchantment that basically says, you win the game sounds super powerful, but since youll be putting over 200 cards in your deck, the odds of you drawing it will be pretty low
If you can manage to do that, though, Shirei is a threat to be reckoned with, especially once it gets a few Blood Artist effects going
For example, if two creatures you control with lifelink deal combat damage at the same time, Heliod's ability will trigger twice
His second ability appears to synergize somewhat with the face commander of the "Scions & Spellcraft" precon, Y'shtola, Night's BlessedY'shtola, Night's Blessed, but only just
Let's see what's heating up
Put them somewhere separate so it's clear they no longer exist