If an artifact or creature has an ability allowing you to sacrifice it for mana, you can't sacrifice that permanent to generate mana and also to pay the sacrifice cost for the activated ability of Makeshift Munitions
If your opponent has to kill your Esper Sentinel with something like Declaration in Stone or Lightning Strike for two mana, you are already winning the exchange, with your opponent having to trade down mana-wise
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Ragavan, Dragons Rage Channeler, and Hammer Time require you to have a certain density of one-mana interaction, so old reliable Lightning Bolt gets the nod
If a spell is cast with an alternative cost that includes mana (such as flashback), Vexing Bauble's first ability won't trigger and won't counter that spell