"Shield" is not an ability that creatures have and shield counters are not keyword counters
Unless they win the game on the spot, or they have some addition to the card, (such as the milling added to the countering of Induce Paranoia) the vast majority of these cards are card disadvantage
Partner (You can have two commanders if both have partner.) Whenever another permanent you control enters, if it wasn't put onto the battlefield with this ability, you may put a permanent card with equal or lesser mana value from your hand onto the battlefield
The Instant Hat Trick will also reward a snappy dresser
Unsurprisingly, a card that fixes all your mana at the expense of one life is going to be one of the more popular competitive options from MTGFINAL FANTASY
Moving around counters creates some incredibly unique situations, but only moving one counter, drawing one card, and Proliferating once means that Tiduss progress will be rather slow