mtg card serach Rules Text: search, your, library, for, a, mountain, 45 cards When the last is removed Spellseeker

Once Mishra's Factory is an Assembly-Worker, it is a legal target for its last ability

Riveteers Requisitioner

On the surface, milling ten cards in a turn for each of your opponents might not seem like much, but add in a few other unblockable creatures and maybe a few effects that let you steal your opponents high powered creatures to attack with, and suddenly everyone is milling tons of cards each turn

The fact that the lands she animates do not gain permanent +1/+1 counters or have vigilance is yet another sign that WotC did learn from the worst excesses of 2019 not being able to switch your brain off and uptick her forever makes all the difference when it comes to producing an engaging subgame for both players