As someone who doesn't play Hearthstone how a card that at the start of a players turn if they have the highest health Creature they draw an extra card, or another where at the start of your turn if you control the highest power card you deal 3 damage to your opponent?

The problem with Hearthstone:
Shit balance, too much pressure to buy packs and expansions. Blizzard cranks out some new cards with OP mechanics and combinations, then lets them run rampant for a while to pressure people to buy card packs... before nerfing them to the ground. Repeat.

The idea you suggested is a part of Yu-Gi-Oh (maybe other CCGs too but I only know of YGO), known simply as "field spells". I imagine if they did add this Blizzard would get flak for aping an existing card game's mechanics.

you could call them enchantments :)

I wouldn't mind more of this if they were represented as cute girls like you used to do.

if there is one card game i could recommend for this series it would be this
https://store.steampowered.com/app/1031140/The_Horus_Heresy_Legions/
never let it be said that even in a world of Hearthstone and Magic the Gathering the Loyalty of Warhammer 40K fans won't somehow make a CCG profitable

Try yugioh duel links.
This comic made me sad..A ccg I played closed and I didnt find out until after the fact. Goodbye Fantasica

Moral of the Story - "It is not the strongest or the smartest who survive, but those most adaptable to Settle The Wreckage"