Glyph of Lesser Energy

Skill details

Full: For 15 seconds, your next two spells cost 10...16 less Energy to cast.

Concise: (15 seconds.) Your next two spells cost 10...16 less Energy.

Energy Storage	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21
Less Energy	10	11	11	12	12	13	13	14	14	15	15	16	16	17	17	18	19	19	20	20	21	21

Acquisition

Incompleted and interrupted spells do count as one of the two castings, but failed skills do not.
If an attunement is active, you will still get the whole percentage of energy back, even if the spell cost you nothing.
Since it reduces the cost by 10 even without any points spent into Energy Storage, it can easily be used by secondary Elementalists as an Energy management skill.

Energy Storage	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
Maximum net Energy gain	15	17	17	19	19	21	21	23	23	25	25	27	27	29	29	31	33	33	35	35	N/A
Effective energy gain/second	0.48	0.55	0.55	0.61	0.61	0.68	0.68	0.74	0.74	0.81	0.81	0.87	0.87	0.94	0.94	1.00	1.06	1.06	1.13	1.13	N/A