You also need to make sure you hit your land drops, either with draw effects (Qiqirn Merchant and Adventurers Airship provide usable bodies as well as draw smoothing) or cards that directly give you lands or mana (World Map, landcyclers, Blitzball)
This is actually one of my favorite parts of brewing up a Spellslinger deck I love nothing more than finding new cards to add to my creations
Players must follow all applicable timing rules for casting spells with the permission granted by Ian Malcolm, Chaotician's last ability
If you have an Asceticism in play, or a Heroic Intervention in hand, you can play without fear
On the other hand, if a spell or ability deals lethal damage to a creature enchanted with an Aura that has umbra armor, the game rules regarding lethal damage cause the Aura to be destroyed, not that spell or ability