Once Sahagin has been blocked, casting a noncreature spell in order to cause Sahagin's ability to trigger won't cause Sahagin to become unblocked
The Precon List Before we talk upgrades, let's take a look at the stock list to see what we're working with: A lot of folks say Hosts of Mordor is an unfocused pile of cards but this is just a poor shallow analysis of the deck: looking at the numbers indicate that it's pretty well-focused on Graveyard and Spellslinger: I count 27 Graveyard cards, counting any card that mills (Forbidden Alchemy), discards (The Balrog of Moria), reanimates (Extract from Darkness), or can be cast from the graveyard (Wake the Dragon)
Vaevictis' pump effect can also be relevant, but poor Palladia gets the short end of the stick - she's just a very big, trample-y dragon
Ulamog, the Defiler (Retro Foil) $76.99 Most Eldrazi titans create prohibitive board states and totally flip the advantage, even if most of these cards have high mana costs
If you choose to shuffle your library, that includes the three cards you just looked at and put back on top of it