Ive been most impressed by Hazoret the Fervent and Experimental Frenzy, as both dodges most of the commonly played removal spells and can single-handedly win the game
In other words, Proliferate lets you put more good counters on your cards which already have good counters on them, and put more bad counters on your opponents stuff with bad counters
And its even better on the rare occasions where characters from different worlds duel each other
Megatron, Tyrant/Destructive Force (8/10) The self-serving leader of the Decepticons Megatron receives a commendable representation in his Magic card as a Transformers Commander, making use of Sacrifice triggers and opponents loss of life to gain an advantage
There are even some Vampires with the madness keyword which means you're able to play them as you discard them
Hes a 2/2 Lifelink, that, whenever he becomes tapped, until the end of the turn, if one or more counters were to be put on a permanent you control, that many plus one are put down instead