So your spell is always successfully cast?
These spells come from the SRD 3.* system. All of Microlite20 is from that source. Unless the spell calls for a test of some sort they are automatically a success... you just have to pay the cost in HP. The difficulty test comes into play occasionally when you are casting against another magic user who can use a counter-spell against your spell, and monsters that have a natural defense against magic.