It is an elemental shield of security using your elemental powers to protect you from any harm the most you can. If for example there’s too much heat it will try using water and cold available to prevent harm and balance you.
Focus and training over the components, some understanding of what and how much elemental energy you have.
Casting Directions for ‘Shield of whatever needed to safeguard’
Meditate. Concentrate on the state of your mind and body. Try to feel what elements are being more then you need at the moment and which ones must be permitted- are less then desired. It is common to have extra of all or most of the four primary elements, but if you feel you don’t have enough of some of these, try to fix that via meditation, food or other type of balancing.
After you’re done with this part chant an international mantra including elements on your mala or bracelet or bangle or whatever you use(it may even be chanted with no artifact if you prefer) to balance and enable your elemental powers.
Focus on your elemental presence and chant: Shield of those elements combined and split, use the influence of my own(it might be different, if you do not believe in separation and individual traits, e.g.-ship or boat or anything) energy by those very same elements to shield me from any harm by balancing anything required to accomplish harmony and wellbeing in every moment of my life as it shall be.
Repeat often and you’ll be protected. This shield may not provide you protection from just anything, but it’ll be of use against irreparable injury and especially powerful against weather extremes. It ain’t extremely good against extreme cold though, but it will still have some beneficial effects to balance what is needed.