100 blocks is too much. It should be 25-40 blocksI think it'll be a good idea for long games like egg wars or tower defense but, not for short games like skywars as it could be used with second purposes.
In order to avoid the abuse of this on egg wars the player would need to on a "safe zone" like a 100 block radius with no enemies, and the player must have not been attacked by a player or dealt damage to one for 30 seconds or so. If not on a safe zone the player would be immediately eliminated from the game.
Maybe 100 blocks is too much... but what matters is the idea.