でWith, By (using)

The particle で has two main uses: the first is indicating the location where an action takes place (e.g., 家で遊ぶ = 'play at home'). The second is marking the means or instrument used to perform an action (e.g., ボールで遊ぶ = 'play with a ball'). These differences can usually be inferred from context, so it's recommended to not stress this too much.

を以て can be though of as a formal version of the basic particle で when used to mean 'at this point in time', e.g. これ（で・を以て）閉会します ('With this, we will end the meeting.'). Note that をもって would not typically be used with the meaning of で indicating 'place of an action', e.g. 大手企業で働く 'to work at a major corporation'.

を以て can be though of as a highly formal/written-style version of the basic particle で when used to mean 'with'/'by means of', e.g. 鉛筆で書く 'write with a pencil' vs. 死を以て償う 'to atone (e.g. for a sin) with one's death' or 'at this point in time', e.g. これ（で・を以て）閉会します ('With this, we will end the meeting.'). Note that を以て would not typically be used with the meaning of で indicating 'place of an action', e.g. 大手企業で働く 'to work at a major corporation'.

The particle で follows a noun to describe the means or method of an action (e.g., ペンで書く = 'to write with a pen'). A verb in the て form can express a similar nuance (e.g., ペンを使って書く = 'to write using a pen,' 歩いて行く = 'to go by walking'). The meaning is the same, but the form differs depending on whether the 'method' is expressed with a noun or a verb.