Since you are f2p, it's hard to find good finishers, as these are mostly Mythic Rare fliers ([[Chromium]], [[Lyra]], [[Seraph of the Scales]], [[Angel of Grace]], [[Doom Whisperer]]). Rare Wildcards should go towards the mana base. [[Depose]] is a nice uncommon you can try. It is multicolor for Hero, helps Thief to get through blockers or provides two fliers in the late game.

I don't think Sinister Sabotage is very good in this deck, as you usually tap out during your turn. Disinformation Campaign also seems lackluster in a deck that doesn't surveil a lot. [[Search for Azcanta]] would be worth a consideration, if you have it.

In general, you have to decide whether you want to play a control deck (counter spells, board wipes, Planeswalkers) or a midrange-tempo deck (around Thief, Hero, [[Hostage Taker]], Bell Haunt and big fliers. Focussing one strategy is better than dipping into both.

I like Revival/Revenge in the deck.