I often find that if I have the mana untapped, people have to assume that I will use it to keep my Fortress alive, and they swing on elsewhere
The last card in the Secret Lair pack is Voidslime, an instant spell that counters a spell or ability for one green and two blue mana
The single line of text on Thromok the Insatiable also reads like it wants a follow-up phrase: Devour X, where X is the number of creatures devoured this way, reminds me of those John Jacob Jingleheimer Schmidt type of songs that loop infinitely back onto themselves
Even without it, it is a 5 mana 5/5 that removes your maximum hand size, and that's a decent floor on its own
It is easy to die to the one drop that resolved or the man land you couldn't touch with a hand full of countermagic
The only real downside here is that not everyone is making tokens, so sometimes its just an expensive 2/2