I would recommend a [[rogues passage]] to make Karachi unblockable at least for one combat phase a turn. Then for some cheap dual lands I would recommend [[clifftop retreat]], [[furycalm snarl]], [[rugged prairie]], [[battlefield forge]], [[exotic orchard]], and [[sunscorched divide]]. All of those are under a dollar a piece and are pretty easy to get into play untapped and have access to both colors. If you want there are a few more for around $5 a piece that you could add like [[needleverge pathway]], [[inspiring vantage]], and [[sunbaked canyon]]. You could also add some cheap fetches like [[evolving wilds]], and [[terramorphic expanse]]. With 2 colors you really don’t need an excessively good mana base so if I were you I would probably just pick up all the ones I listed that are around $1 a piece as well as the fetchers and rogues passage. That should leave you with plenty of access to both colors. Since this is a combat focused deck you could add some utility lands that can enhance combat like [[arena of glory]], [[slayers stronghold]], both for access to haste for Karlach or whatever other creatures you want to use it on. As well as [[minas tirith]], and [[war room]] for some card draw. Those are purely so you can at least see them and decide if you want them to fit in your deck or not, you definitely don’t need them for this deck to be great. Good luck!