Shimmer Myr

Flash
You may cast artifact spells as though they had flash.

Lodestone Myr

Trample
Tap an untapped artifact you control: Lodestone Myr gets +1/+1 until end of turn.

Imprint — {T}: Exile target artifact card from a graveyard.
Myr Welder has all activated abilities of all cards exiled with it.

{T}: Attach target Equipment you control to target creature you control.

When Myr Retriever dies, return another target artifact card from your graveyard to your hand.