saproling mtg cards Slimefoot, the Stowaway You may cast Saproling Symbiosis any time you could cast an instant if you pay 2 more to cast it Saproling Symbiosis | Invasion |

At the beginning of your upkeep, distribute two +1/+1 counters among up to two target creatures

Captain N'ghathrod Consuming Aberration Dinrova Horror Etherium Abomination Horrid Shadowspinner Krothuss, Lord of the Deep Mindleech Mass Nemesis of Reason Psychic Symbiont Uchbenbak, the Great Mistake Umbris, Fear Manifest

The Game Awards After Party allowed Arena players to try out Elspeth, Suns Nemesis

Top recommendations Golden Fluid and Model Air, can be used straight out of the box with their thin density, you can easily mix and apply to the card

Summon: Fenrirby Chun Lo

So, yes, you can proliferate an enemy summon to death