My deck for Masters this month.
I don't think you need any more pledge units; I failed to find a pledge unit two or three times from gold rank to masters. Apex Predator is the only unit not in the deck that would make sense, but it is way too slow for the deck. Gunrunner is a decent card overall, but I like it more in an aggressive version.
Vanguard and Cykalis are both great to pledge, but generally Vanguard is the better option.
Purify is simply here to counter specific cards that would otherwise completely stop this deck, most notably Silverwing Courier.
There's a lot of fire sigils in the deck compared to time sigils, despite the deck being ~70% time. That's because the plan is to pledge for time T1 most games. I'm sure it can be optimized somehow, but I found this balance to work really well.