Feral Strike

Feral Strike
Ultimate SpellCost: 4
Boost ④ (You may pay an additional ④ when you play this to get the boost effect.)
Choose one: Fetch up to two units from your codex, reveal them, then put them in your hand; or put up to two units from your hand into play if you have tech buildings of the same tech level as them.
If you boosted, choose both.
GreenFeral Ultimate Magic

Card-Specific Rulings
"If you have tech buildings of the same tech level as them" means that for tech 0 units you only need your base (which you always have if you haven't lost the game yet), for tech I units you have a tech I building, for tech II units you have a tech II building and for tech III units you have a tech III building. Your building does NOT need to be the same spec as the units. For example you could use Feral Strike to put two Blood tech II units into play, even of your tech II building was Growth spec. — Sirlin
Boost X Rulings
If something has you "put a unit into play," that's different from "playing it" so you can't pay for or use a boost effect in that case. Likewise, if a unit with a boost enters play through any means other than playing it (such as being returned from Second Chances or Geiger or Pasternaak's max level abilities) then you can't use its boost. — Sirlin
Using Graveyard, Jurisdiction, and Vir Garbarean you can "play" a card from a zone other than your hand. You can still use boost when playing a card this way. — sharpo
If an opponent has Jail and you play a unit with a boost, you CAN pay for and use the boost. You do that immediately as you play the unit from your hand, then the boost effect happens and your unit goes to Jail. When it leaves Jail and arrives in play, you do not have a chance to pay for or use the boost a second time. — Sirlin