You should proxy cards that you dont have, cards that you own that are very expensive and youre trying to preserve, and ones that you intend for casual play or events that allows proxies
The results were evident: in Mythic Championship IV, on July 27 and 28, 2019, Hogaak remained the most played deck in the format, with 21.4% Metagame share, while Leyline of the Void was the card most played of the event, with 836 copies - despite this overwhelming number of hate and preparation against it, Hogaak still managed to establish a 56% win rate in one of the highest competitive level tournaments in the game
For example, if you control The Ozolith and Host of the Hereafter when a creature you control with counters on it dies, you'll put the appropriate number of each kind of counter onto both The Ozolith and the target creature
This card has many applications, and youll be seeing it in decks like Samut, Voice of Dissent, and as a value piece in general