The only downside to such cards is needing to be a bit heavier white to reliably play one mana spells on turn one
Shorikai has an incredibly high power ceiling, being able to go infinite with Intruder Alarm and doing evil things with Unwinding Clock and Skullclamp which are outside the budget range of this deck, but they are available if you want to upgrade
He's one of the best proliferate cards available in Jund colors, and when you play him, assuming you've done your job and spread counters around, he'll have a massive impact the turn he comes down
There are plenty of new ways to play the game as well
A very interesting MDFC design, its easy to replace a Plains in your deck for this warlock from Modern Horizons 3
He summons Curse of Dragon (2000 ATK) and ends his turn, and then Yugi takes control