Hex Parasite

{X}{B/P}: Remove up to X counters from target permanent. For each counter removed this way, this creature gets +1/+0 until end of turn. ({B/P} can be paid with either {B} or 2 life.)

Phyrexian Metamorph

({U/P} can be paid with either {U} or 2 life.)
You may have this creature enter as a copy of any artifact or creature on the battlefield, except it's an artifact in addition to its other types.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Etherium Sculptor

Artifact spells you cast cost {1} less to cast.

Solemnity

Players can't get counters.
Counters can't be put on artifacts, creatures, enchantments, or lands.

Noctis, Prince of Lucis

Lifelink
You may cast artifact spells from your graveyard by paying 3 life in addition to paying their other costs. If you cast a spell this way, that artifact enters with a finality counter on it.