That's a severe double-edged sword to dance around, but fortunately, fellow denizens of the underworld are here to help
Turn one Sol Ring into turn two four-mana play represents a tempo advantage that opponents struggle to overcome
Ghalta, Primal Hunger Ive seen this creature be cast as early as turn 3 or 4, and I can imagine some play patterns allow you to cast it even sooner
Thelon's Curse on the other hand forces your foes to leave their Blue creatures tapped
2) Strong Back Like Grim Reapers Sprint, Strong Back adapts a perk from the Fallout games into an Auraspecifically one that makes the enchanted creature cheaper to buff with equipments and other auras, and makes it stronger for each of those buffs it has
The indestructible counter will hopefully allow you to take advantage of the doubling effect and reduce the effectiveness of your opponents board wipes (the scourge of token decks), and makes Mondrak an excellent token commander